im either going to buy a ex5, a trinity or someone suggested roland can deliver some nasty raunchy evil basslines, thats the sound im lookin for, i know the ex5 is really really good for those type of sounds but its timing is off, and the trinity sounds too digital like a robot. any suggestion for a keyboard by roland? peferably something thats 128 polyphony at the least.

128 polyphony?? I dream. Good luck, seriously, if you find anything please plaster it right across here, 64's the norm, may I ask why you need so much??
As to the Roland boards, I find that I can tweak most stuff to sound how I want it by using other sounds on the backing, pretty much use your ears, go a big shop, and irritate the staff by playing through an aftyernoon or something.. I do hehe...
Al

Element hi...
I will not tell you what synth you must buy or not. Just don't believe marketing lies like 128 polyphony. You can read many magazine and web articles about polyphony issue. As Al_a_man told you expect 64 or fewer voices even from "128 voices" synths. Take a look on Yamaha's S80 or Roland XV88. Both have some excellent sounds and effects. For analog-like bass sounds try S80 plus PLG150AN board and expect 16 voices polyphony + onboard 32-64 voices and for digital basslines S80 plus PLG150DX for DX7 like basses.
In Roland XV88 case you may expect 32 - 96 voices max polyphony on basslines with excellent bass reproduction but for a higher price. Roland has nice bass sounds some of them analog like.
There are also more expensive solutions, like Kurzweil but also don't expect more than 48 voices.
In my opinion as bass are mostly lead parts buy a cheaper keyboard like Yamaha S30 that is 61 keys version of S80 and spend the rest of your money for a good digital multitracker solution like a good direct hard disk recording card on your computer. That way you'll have the best sound and as many voices you want (on multipart recs).