I'd personally pick AccessPort over UTEC any day. The AccessPort tune is more like a ECUtek tune in regards to safety. Since it uses the stock ECU and reprograms it, all the failsafes are there. UTEC fools the ECU by sending it very well defined but faulty data, so the motor doesn't really know whats up.
StreetTuner on the other hand is a perfect opportunity to really push the limits of your cars tuning, much in the same dangerous ways the UTEC can. It can be a powerful learning tool, but its also quite dangerous IMO.
Of course, I'm really an ECUtek fan, so you'll find me there first.
But as an alternative, I much prefer AP over UTEC.