My take on all this...
Seagate drives aren't the fastest, however their published specs may be closest to reality. Look at the recent Storagereview.com 250GB drive roundup. The Seagate had the slowest published seek by far, but when actually tested the other drives couldn't even come close to published specs.
Reliability or not, there's warranty. IMO all drives regardless of size/brand/model will have failures. Seagates may look like they are failing at a higher rate because likely more people are buying them. Who knows the actual percentage of failures, but the numbers are likely to be huge. For instance let's say that a 300GB Seagate has 1000 failed units in a month while a 300GB Maxtor only has 500 failed units in the same month. Does that mean Maxtor drives are more reliable? Well, if they sold the same amount then yes, but what if Seagate sold 20,000 and had 1000 failures for a 5% rate while Maxtor sold 5000 and had 500 failures for a 10% rate? I'm just making up those numbers, but the fact is that Seagate is the largest HDD manufacturer in the world in volume, and that's a fact.
As for $/GB, that's fine except I like having fewer but larger drives and the 300GB is at a sweet spot because going from 200GB to 250GB is almost the same price, and $20 more for the extra 50GB, but then for another 100GB it's $130 more, so the 300GB drive price point is the best for maximum capacity while still being cheap on the $/GB.