I've ued both of those combos, and quite frankly, the Sentinel wins hands down. I started and built up most of my achievements with a Sentinel, and never got sick of that class. AI Hacking + Singularity > everything. Nothing can touch you.
If you want more advice, hit up the wikia page
. It's got awesome builds and strategies.
I'm playing through as a Vanguard now, and it's pretty bleh. I use Wrex and Tali for the balance. Wrex in your group with any class is always a good investment, lol. He's just too awesome.
On another note, I got my Pinnacle Station last night via EA Store. It doesn't make any sense. They honestly should stop charging for it.
It'll probably be one of the last things I do in the game even after BDtS. Just wanting to steer clear from it until I'm done with the game since it got such horrible feedback. Ah well, no skin off my back since it was free.