I'm now on my 3rd HTC in a row, before that was a nokia N95.
Firstly I had an HTC Hero, build quality was fantastic but it was as slow as sin, mind you as soon as I changed from the stock ROM it was a pleasure to use, though I suppose that doesn't count. This lasted me 18 months
I then went on to an HTC Sensation, a perfectly capable smartphone built like a brick outhouse, I had it for 21 months and it's still in use as a hand-me-down in my family to good effect. This was still the period where HTC outshone everyone with software then scrimped on RAM etc, it was a lovely phone to use but couldn't quite match the SII unless it was rooted, which I did, allowing me to use something a little lighter than Sense to make sure it didn't gum up after a few days use.
Finally, I'm currently the proud owner of an HTC One and, frankly, I'm extremely glad I didn't go for the S4 instead. It's beautifully built, the UI is as slick as they come (I frankly think touchwiz looks and feels a bit cheesy) and it's more than powerful enough for what I do, I'm not a mobile gamer and I won't be doing anything else especially intensive to even warrant it's 1.7 quad core, but the 2gb of ram makes sure there's no slow down and everything about the phone is snappy. Yes the S4 will scroll for you among other gimmicks, and it's a slightly faster phone, but it just doesn't look or feel as well built. I'm saying it doesn't feel as well built without having held one, but seeing as it's made out of plastic rather than metal I don't think there's anyone who will disagree.
I have always loved HTC Sense and now the One comes with the memory to cope with it, I can't see any reason I wouldn't go for the next big HTC in 2 years time, but only time will tell.