Revisions
DARK
Pyramid - Fast Decay, lots of bass and mids, light top end. very "old school" sounding. medium tension. They'll thump (come out the box broken in).
GHS precision - very well balanced, decent bass mids and treble, Low/medium tension, just again a balanced string. They'll thump (take 3 months break in to sound good).
Ernie Ball - well balanced and similar to GHS but high tension. They'll thump (break in is quick)
Labella - good bass and treble, scooped mids. low/medium tension. They'll thump (break in is quick)
Optima RB - good bass and treble, slightly scooped mids, low/medium tension. maxima reproduction supposedly. They'll thump.
DR - Similar to GHS overall that they are well balanced, but add more top end. Sound like a flatwound Lo-Rider. They'll thump.
Chromes - Good Bass, scooped mids, accented treble. high tension. They'll thump (after 1 year of playing though)
Rotosound - light bass, decent mids, accented treble. medium tension. More flat grind than thump.
TI - light bass, heavy mids, accented top, woody nuanced sound (the further up the neck the sweeter it sounds). Low Tension. The decay/envelope on these doesn't sound like a flat to me, the low E doesn't die/decay, it stays strong like a roundwound. No thump, very punchy instead.
BRIGHT
some of the best descriptions I have heard, pure gold in this post!
I have flats on almost all of my basses, I dig the feel and vibe and the way they make me play. I also find that the bass they are on is really key to getting the best from the strings in combo with the instrument... some just fit each other better than others... so below I attempted to list the stings I have experience with from Dark to Bright and the basses they live on that have jived the best. Also probably worth mentioning is that all of the below basses are passive. Grain of salt as this is, of course quite subjective and as they say.... YMMV!
DARK
Labella 760FS - P-bass -THUMP
Labella 760FX - Single coil P-bass -THUMP with a bit more highs and a more even playing feel.
Fender 9050SL - Single coil P-bass -THUMP with More Midrange. high-ish tension.
Chromes ECB81 - Fretless P-bass type/ebony board (Dimarzio Model P's) Lots of highs and lows, take forever to calm down. high-ish tension. I always roll the tone down with these strings.
TI Jazz Flats - Rickenbacker 4003 - woody, organic, balanced, midrangy, not super bass-y or boomy, highs are there if you want them. lowest tension.... I have to back off on my normal attack but it is totally worth it.
Cobalts 2813 - Fretless/ebony board (humbucker)
Cobalts 2815 - Jazz Bass (Dimarzio Model J's)
LIGHT
Cobalts are easily far and away the brightest flat I have used and I love them, they can wear many hats and can be almost round-like minus the finger noise. Very even tension, clean tones, balanced low/high/mid but very forward sounding. I feel like I could rock these in any setting any style. I really like these. In the future I will be trying a set on the Ric for sure, I think that would be a really good match.
If I had to choose only 3 it would easily be the Fenders, 760FX's and the 2815 Cobalts to cover a range of sounds on any bass I own.
2 cents for the masses....