[quote name='shrike4242']What about the Sentinel? I was thinking about that class as my second playthrough character when I get over from ME1 for the second time. That, or the Adept.[/QUOTE]My main problem with the Sentinel is that, although it provides you with every offensive ability that you'll need, it does not make you a master of any of them - the proverbial jack of all trades, master of none type of scenario. Because I prefer to have Miranda and Kasumi with me at all times, I feel like Shepard does not necessarily need Warp and Overload in order to be successful in the game. In my case, Engineer or Adept fits perfectly because:
With the Engineer (and Miranda/Kasumi):
I have all my bases covered without too much overlap - Incinerate, Overload (x3)*, Cryo Blast, Warp, Flashbang Grenade, Shadow Strike, and Combat Drone.
Incinerate - stops health regeneration (Vorcha/Krogan) and melts away Armor, also sends normal enemies into panic.
Overload - takes off Shields (which everyone has on Insanity), destroys synthetics.
Cryo Blast - crowd control; allows you to do 2x damage for its duration.
Warp - Barrier destroyer and stops health regeneration.
Flashbang Grenade - crowd control; jams enemy weapons (especially Harbinger's - he becomes unable to do anything until the grenade's effects are gone) and leaves them defenseless for long periods of time. Also knocks unshielded enemies out of cover.
Shadow Strike - efficient way to finish off enemies in cover.
Combat Drone - excellent distraction for tough enemies, especially the YMIR mechs.
* Overload is extremely important on Insanity.
With the Adept (and Miranda/Kasumi):
One phrase - Singularity detonations. (also Overload x2, Flashbang Grenades, and Shadow Strike. I prefer Energy Drain for the Adept in order to have a pseudo-Overload)
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For me, the Sentinel has waaay too much overlap and you lose the Combat Drone and Incinerate which are important (depending on squadmate choice). I also didn't find the Armor to be all that effective and it hogged the cooldown meter way too often. If you prefer others to Miranda and Kasumi, then another class besides Engineer or Adept may make more sense.