Tech classes are a decent choice since the Tech skills are good and you can finally have some party variety since you won't need to keep Tali or Garrus in your party to open locks.

I actually went boring with Commando and kind of regretted it since it made it nearly impossible to use Ashley and Wrex since their builds are too similar and having a balanced party is much more important in this game than in the sequels. I say go with a heavy Tech class or Adept since Liara is kind of... stalkerish.

Avoid Sentinels, they kind of blow in this game because they truly embody the Master of None trope. They are only really good with pistols and they get a poor mix of Biotic and Tech abilities that can be better utilized by other more specialized party members. I have never regretted my decisions concerning Kaiden.