I played metal for most of my "career", all theese years I've looked for "The sound"(in my case the pantera sound from great southern trendkill). I've played punk, old heavy metal, hard rock, thrash metal, death metal, nu metal, speed, progressive metal and so on.
When it comes to settings, they are what u make them, but low string height is a advantage when I wanna play fast, do hammer ons etc. also active electronic is a good way to easy close in for the sound I look for, but as ever it depend on what kind of music you play for the day.
In order not to have to buy 1000's of gizmos to achive the ultimate soud in each genre I think knowing what general sound you're looking for, and then investigate ways to find it and the start buying gear that will allow you get that sound, but also if you wanna play other styles to adjust to that. Todays multiFX things are staring to get close to get all that into one little box, but for me, it's not enough, I wanna have the exact copy of teh sound I have in my head, in my amp, and the raw power to push it out through all the guitars and drums. After I found that I realzied that I can't bring all that gear on a plane or in a van.
Remeber that if you use a pick you'll get a mroe agrressive sound than with you fingers(if not playing slap), you can also youa rubber pick to generate a "finger simaulation", it's sounds somewhat like playing with fingers, I needed to change playing technique a bit thou.
Strings: I use EBS Northern light strings or Daddario half rouns strings. They are fairly cheap and give me a nice sound
Pick a bass: I have 2 ibanez 5 strings, mostly cause it allowes me to play both regular hard rock and also low tuned newer metal, and the pic up's and all are mostly fitted to give you enough feedback from what you play to satisfy you. I also use a LTD Tom Araya bass, 4 string. Not the best but to the worst, if you adjust your pre amp/amp settings you'll find sound that you like.
Music man sting ray is for me probably one of the best sounding basses in general. It has the classic tone that you wanna have from a rock bass, a little bit thicker sound than for ex a Fender. But most of all, it delivers a much more even sound. The problem with many basses is that the lower notes/strings generates so much energy compared to the higher notes/strings that i most situation a sound engineer will neeed to use a compressor to even out the levels, but this also kills a lot of the actual sound( I prefer a multiband compressor for bass when possible), but the music man makes the use of a compressor to a minimum.of course there's other basses that has that quality aswell,but just a example.
Amps: I currently use Ampeg SVT2 Pro, it's a nice rock amp, that are pretty close to the ideal sound for me. But it's heavy as h*ll... But today a lot of nice amps are out there.
I also have a old Acoustic amp, it's in ****** condition but if twist and turns the knobs I can find nice sounds that fit many styles.
The only thing that might be a problem with thoose is that in some cases I get the impression that they might have some lack of precision in the low freqs, they just rumbles on, but that's why I have the SVT 2 pro for, due to the extra EQ, there at least I can filter out some freqs. But a trace elliot or hartke have more distinct and precise low end. and are much cheaper...
Cabs: I play with ampeg cabs cause to be they fit me perfect. I'd say that a hartke with thoose "silverglimmering" elements are nice for more attack, such as red hot chili peppers or primus music. If you play detuned music(5-stinged music for ex.) you'd need some cabs(and amps) that are capable of delivering the tones at the needed volume, it'd must move "more air". So in a loud metal band playing the "no dynamic" full force songs, you need to be able to cut through. I use a ampeg 8x10" and/or 2x15" there, but live you need to be careful, cause the cab "throws" sound a long distance, so when you feel that you finally hear your amp on stage, the people in front of the stage most likely go insane of all the bass. therefore i'd recomend a 4x10" or 6x10", playing lower so you just get the warm low end in your back a bit, then you make sure that you get the rest of what you need in the monitors. I will come back to this later.
Di's/pedals: I use a Tech 21 SansAmp bass driver, it can giveyou a huge variety of sounds, and the fact that it works as a D/I box is great. When there's enough monitor system I only use the sans amp with some other pedals, no amp. The only thing with it is that you have no real EQ, therefore I'd also put a EQ before the SansAmp.
EBS Walvedrive: EBS is a swedish brand that make excellent gear for bass use. I use the walvedrive both as a distotion pedal and as "basic tone" pedal. It has the same lack of EQ as sansamp, so I'd put a EQ here aswell. but it is walvedriven wich gives a nice sound, you can also switch between modern and vintage sound, the vintage sound get's the sound more raw(sabbath, old metallica, anthrax etc) and modern wich cleans up the sound a bit.
EQ: Hard one, I don't like pedal EQ's that much, they are to inprecise, a real dedicated rack one will do the trick, there you can cut or boost freqs as you like depending on the needs.
of course, cables and picks are as important, harder picks, more agressive sound, real cables are nice, but in a live situation, the difference is so small you won't hear it, unless the cables are broken.
Ok, now over to more specific what I'd use to get the sound you asked for:
early thrash: This is normally not that detunes(D# to D, rarley more) I'd use a long scale bass(34-35")fender, music man bass(humbucker/single coil comb), a amp that comes to mind is SVT classic, I'd cut the treble a bit(depening on the bass) and also make the low end more defined/precise with a EQ, also make sure that you keep the mid EQ up. Fingerplaying is prefered but pics will make it eaiser to keep up with te speed. I'd also distort the sound sligtly to get a more "compact" feeling of the sound.
Speed/later thrash: same gear, more edgy EQ in the treble and more of "loudness curve" over all by cutting the mid a little. The distorion can also be abit more agressive, not much though. Pic is to be prefered.
early grindcore: Here I'd use pretty much the same bass, maybe a bass with single coil with do, but if you already have the humbucker, just switch to single coil(or humbucker with less bass will also do it), The amp wouldn't be as important, solid state ol walve, but it should have a pretty defined aprecis bass response due to that I'd put on pretty much distortion(raaaaawwww), so i wouldn't blow up the speaker later
, i'd use a distortion pedal, I use mu walvdrive, but a boss overdrive is also ok. make sure that you don't distort to much, all people will hear is a noise when amplified through a PA and no tone. Us a pic. If detuned to D or more(no rule, just my opinion), 35" bass is nice.
Later Grindcore: Like earlier, but i'd might clean up the sound a bit, also a 5-string here with humbucker mics. Play with a pic. Tace elliot or hartke amps would probably do it.
Black metal: The primitive black id make sure that I'd have a lot of mid, maybe run a regular Ibanez SDgr through a guitar amp(marshall for example), for the more dimmu borgir sound I'd use a 5 stringer long scare(35" like ibanez BTB) with a cassic rig or a line 6 bass pod pro xt and find a setting there I'd like(there's some carlifornia preset I think that is ok)
Nu metal/hardcore like pantera: 4 or 5 stringer with humbucker, pic playing. I'd use a sansamp + the EQ, a SVT 2 Pro, or SVT classic blue line, I'd use 2 separate D/I's, one before and one the sansamp(this is actually how Napalm death do live but with tons of distortion), I'd use a EQ to find the right mid freq to turn down, but also boost a lower freq where you'll find that your bass will give you warm and defined tone, I'd also keep the attack from the pic, then I'd take the treble/attack and make make them come through the pre sansamp signal, and the low end from the post sans amp, i'd distort the sansamp a bit, you should be able to get a warm sound that still are agressive and not that "rumbly".
vintage: simply take the fender bass or a rickenbacker, a svt clssic rig with a 8x10" or a orange rig, play with your fingers and you should be pretty much there.
The mid 60's Id make sure that I have a fender or similar. I'd play with a pick, use a amp that gives me a clear low mid tone(2-300 Hz)
The late 60's, the same but with a bit more overdrive in the amp.
Doom, stoner: Rickenbacker with a acoutic, ampeg svt or orange rig. detuned into A-D or something you will get a thick sound with a lot of bass and less attack. maybe a big muff pedal or something to make a fuzz bass sound.(i'd throw on a EQ then to control the sound more)
NWOBHM: The fender bass would be nice, or a ibanez, standard or detuned to D#. Saxon uses a sansamp as the base for their live sound(don't remember their exact live config now), they used a on loaction peavy bass amp at the gig I was, but a peavy Mark III or something would be nice, but once again, the sansamp...
Hair metal: hmmm... i'd use a singe coil style bass(like i said, a humbucker would also do), gibson thunderbird, Svt classic, mötley crue style id keep it warm, a bit overdrived and not to edgy, skid row style, more funky with same overdrive but more treble.
Ygwie etc: Any gear that dosen't inflict with the guitars
Lemmy: All I know, marshall guitar rigs on 110% max!!!!!
I appreciates it. 
