The only brand I particularly avoid with SCSI is Fujitsu due to their extensive and persistant quality control problems. I personally have had good luck with Seagates, but I'd say most everyone's going to be a fair roll of the dice, and I'd recommend using value as your deciding factor rather than anyone's particular brand loyalty.
for SCSI Id recommend seagate, the IBM may be a little faster but seagate has the better reliability and warranty. Note thier 15K RPM 300GB SAS drives just released, if you want that kind of speed you gota pay for it.
1) Nobody, that I know of, is selling the 15k.5s yet. It's a paper launch. And I don't want to know how much that sucker's gonna cost.
2) The MAT3300 is at the top of the leaderboard on StorageReview, and is pretty cheap compared to the Seagate. And Fujitsu's warranty is five years for 3.5" scsi drives; so is Seagate's.