For us, the worst drives have been WD raptors. We've rma'd 14 outta 25 we've purchased. No more believing the HYPE. Total Crap but at least they have a decent warranty
Maxtor we have returned a few.
Seagate has been a very solid drive for us actually (looking thru inventory).
Samsung? Never bought one except I believe my old laptop had one and we had to replace it - might have been hitachi though, dont recall.