I have a T100 and really like(d) it, but I did just buy a new Tacoma. I decided that I wanted a new, more comfortable, safer (airbags, ABS etc) truck with doors to access the area behind the seats. And this may be the last vehicle I ever buy. And my T is for sale now.
That said, the T100 is a really good truck. It's been reliable, and honestly, the size is just right. I find the 3.4V6 more than adequate in the horsepower department, even with an automatic. I don't tow, but deal with mountains and altitude and it does just fine, though I'd have preferred a 5 speed. Mine is a DLX 4wd XtraCab and the cab is roomy and even the back seat is quite usable by adults for short distances ... the hassle is getting people or gear back there. I've never driven or even been in a Gen1 Tundra, but I've heard the Tundra cab is less roomy due to thicker seats, console, etc (comparing AccessCab to XtraCab) but of course you have the extra doors, or could buy a DoubleCab. The new Tacoma is light years more refined than the T100, but I've driven FJ60's and owned an FZJ80 for years, and I'd say the T100 is peppier and better handling than the FZJ, rides slightly rougher, and is far more pleasant to drive than an FJ60/62. Oh, the 60/40 bench is pretty bad.
I've hauled 1500 lbs of gravel in the bed of the T100 and it felt fine. It's much more heavy-duty than any Ranger or Frontier. And though used prices are high, seems a better value than a Gen1 Tundra, at least in the California market, unless you really want the V8. Oh, and the T100 AccessCab is shorter than a Gen2 or Gen3 Tacoma XtraCab, and has a much wider bed. Good truck! Now, why did I just buy a Tacoma for the price of 4 or 5 nice used T100's? Hmm ...