I am a fan of Fujitsu. Have been using a T902 for about 3 years - works great. Prior to that, had a T4000 (I think) that lasted me about 5-6 years in spite of a case-ruining drop (that I subsequently fixed). I will likely replace my T902 with a T904.
These are hybrid Windows Tablet PCs built for enterprise users so I tend to buy them refurbished from Fujitsu (on eBay or directly). IME, they are very upgradable, very high quality, and with unmatched customer support.
I bought a preloved 7yo Toshiba from the local pawn shop for $AU50. It came with a 3 month warranty but is still alive 7 months later. Specs are adequate for my university studies.
Replacement 3 hour battery for $AU15 + shipping on ebay. I didn't check what a "genuine" one costs or if they're even still made but I suspect it would be more than I'd paid for the machine.
It seems like economies of scale have steamrolled quality. If one company can sell 1000x the volume to people who don't know better, then even those who do know better will often find the high-volume choice more practical due to cost and industry support just being too good to ignore.
Yeah i find myself reminded of an anecdote about a young lady that wanted to treat herself after landing her first job out of college.
So she went to market somewhere in Asia, fund a stall selling handbags, and started to haggling by pointing out the various ways the bags where fake.
Eventually she settled on a bag. She knew it was fake, she knew it would not last as long as the real thing, but she hoped it would at least hold until she climbed the corporate ladder enough that she could replace it with the real thing.