I was speaking to open reel decks above, but, yeah, their cassette decks up to the 122 Mk. III are good. After that, they were on the wrong side of the CD and went downhill fast. Most techs agree the 122 Mk. II is the pinnacle of Tascam cassette decks (for a conventional deck and not a multi-track or other special use deck at higher speed). More and more plastic, crappy heads, watered-down electronics etc. Just built to a price point and no quality concerns. I don't even think you can get a balanced in and out cassette deck after the Mk. III... (I don't know of one anyway). Maybe the 112B was still available but that's a 2-head ("B" suffix indicates it has balanced in and out). I actually had a 112B for a while as a digitizing source for my old cassettes. Decent, VERY decent play deck, but not the best for recording, unless you set it up for one tape and don't vary from that.
The 122 Mk. II and Mk. III both have on-board tone generators for the fine bias and level adjustments. The first 122 is adjustable, but no internal tone generators (I had one of those before the 112B but lack of test tones was a bother). However, you can see/feel the build quality decreasing through the life of the 122. The Mk. III has some other functions I like as well, but the "ultimate" three-tape-type performance will be had with the Mk. II.
And if you care about balanced in/out on the open reel decks, you generally do not find this on the Teac offerings- it was a Tascam thing, and even then, not on all of them. I prefer to run balanced for all the recording/tracking/mastering activities. It won't matter much for basic ripping and playing.