The GE Superadio series is good, of course. The Superadios have chips as well as discrete transistors, so I don't know if that falls within your definition of a 'transistor radio'.
The Radio Shack, Realistic TRF models (12-655 and 12-656) are very good. The Realistic TRF 12-656 has an audio chip, but the RF and IF circuits are all discrete transistors. The 12-655 is all discrete transistors. They'll pull in about everything a Superadio will pull in.
Several of the early GE AM radios were very good -- the P780 is maybe the most famous model. There are a couple other early GE models with RF amp transistor sections that were good, some of them having only seven or eight transistors, but pulling in about the same amount of DX as a Superadio.
I have an old GE four transistor clock radio that actually DX's fairly well considering it's only got four transistors (converter, IF amp, audio amp, audio output).
A lot of the transistor radio fanatics swear by the Channel Master brand of radios. They apparently are very good for DXing.
The Zenith transistor TransOceanics are reportedly very good on AM. They can cost a bit, though.