Don't pick based on the phone, picked based on the coverage, which is more important to 99.9% of the people. The 8290 is a GSM1900 phone, and the coverage for that network is extremely limited when compared to the TDMA 8260. People like VoiceStream, PacBell, and Nevada Bell sell the 8290. ATT, CellularOne, Ameritech, Southwest Bell, and the likes, use the 8260. So check up on coverage. You may not even be able to get covered with the 8290.
If you have a choice of either, I'd go with an 8290.
If you have a choice of either, I'd go with an 8290.