if you go for the 840, make sure it is the 840 pro. that is really the only way you will see a speed/performance difference when compared to other ssds. relative to the pricing for ssds, you can catch a nice deal if you time it right. i know that frys had a one day sale on their 240gb sandisk extreme ssds for only $158! that is the drive i use, and i almost bought another one at that price. in comparison, the 256gb 840 pro will run $220-240 "on sale".
so brand wise sandisk is good obviously because they have been in the flash memory business for a while. the corsair ones are really nice, especially the red colored one (i think its a gtx or something like that cant remember the model name
) depending on the model of the ocz drive you chose, they can actually be pretty nice. i as a rule usually stay away from them in builds. definitely stay away from muskin, too many wishy washy reviews for my liking on that brand. intels are niced, but like almost everything intel, overpriced imho (im talking motherboards and ssds here not cpus as much so please dont start a flame war with me other posters). well for the performance level ssd wise, stupidly overpriced. patriot pyros are nice but i havent seen anything new from patriot ssd product wise so im not sure what is up with that. oh and of course, crucial m4 ssds are nice. plextor ssds are pretty much the same as crucial m4s performance wise (m3 at least that is). lite on ssd (if you find one, reasonably rare) are just the dell oem version of the plextor? or the crucial? cant remember which one, but pretty sure one of those. let me know if you come up with any other brands, i believe i have named the most prevalent (and not so much) ones.