My .02
Cheapie EBO - Junk
Cheapie Bronco - Junk
Turser Violin - Not bad
RumbleKat - Very nice, but I dont like the rumble tone of the shortscale combined with the hollowbody.
Gretsch - love to try one.
SX shortscales - Lots of experience with these. I've owned 4. The SX ss J is wonderful. Expect to get a pro fret job and setup. That makes a world of difference and turns a ho-hum bass into a bass really worth playing. You can get an SX J ss in ash (but have to buy a fretless (thats all they have in stock now) and buy the rosewood block fretted neck as well... which is an extra $40). The ash is nice because it adds more attack which helps the tone profile of the shortsacle. I did a crap load of upgrades on mine and now its just a fantastic bass. Two upgrades that make a world of difference is a set of Model J pickups and a BA II bridge... that and a good set of strings and you have one great bass IMO/IME. One more thing I would definitely do is replace the cap with an Orange Drop. Very worthwhile mod there.
The SX ss P is also great. However, be warned the neck is DEFINITELY smaller than the ss J. I actually had my ss P routed so that it would accept the SX ss J neck. I did that because I wanted a rosewood neck and the SX ss Ps only come with maple.
I've also owned an SX ss Jag style bass. Looks awesome, sounds like a J, but the neck dive is terrible. Dont bother with that one.
My take is to buy the SX ss J (if you like a wider neck or rosewood neck... if not buy the P) and over time, or as you feel necessary, do the mods to make it an excellent bass. The great thing with these basses is that the wood is pretty good quality. Real wood, not plywood or junk. So as you can afford to, you can upgrade each component and in the end have a really nice bass.
Priority one is getting a pro fret dressing and setup.
My bass (still have to get a proper pic):
My SX ss P before the neck switch to rosewood:
Stock SX ss J fretless:
http://www.rondomusic.net/product2462.html