People are getting more mileage out of these TI systems every year. Ports of classic Zelda, F-Zero, Pokemon, and Mario Bros 3 were announced recently, and the RealSound project demonstrated the TI-84+ can play CD-quality audio. There's even a PAL video output program. Some people even use them for math still.
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TI-84+ SE is really popular. Probably it's the closest fit from your TI-86.
TI-89 Titanium gets good reviews. Basically, it's a TI-92 you can use in SAT/ACT. Everything your SAT proctors hate.
N-Spire is their new high-end model. It's powerful but has programming restrictions that make it irredeemably developer-unfriendly.