Which (combat) playstyle is most fun?

Explorer with the following skills:

Incinerate, specced to both prime and detonate
Energy Drain, specced to both prime and detonate
Shockwave, specced to both prime and detonate

It's like you're in your very own Michael Bay movie.

Did you try the Isharay sniper rifle for your Infiltrator run? If not, I can highly recommend it.

So far I played three different styles - all on Insanity:

1) A biotic who experimented a bit with tech powers (a real explorer). Singularity, charge and energy drain. A pistol (Carnifex) and a sniper rifle (Viper) as back-up in case I needed some range.

2) An engineer/infiltrator combo. Tactical cloak, incinerate and energy drain. Again a pistol (Carnifex) and a sniper rifle (Isharay). This time the sniper rifle being option 1, so I went with more punch.

3) A sentinel type. Annihilation field, lance, energy drain. Shotgun (Dash) and sniper rifle (Black widow).

All three were a lot of fun and despite energy drain being on all three (because I like this power's ability to prime and detonate while also restoring your shields) all of them felt totally different.

The first is of course the most dynamic, charging all over the field and having two powers that prime and two that detonate meant a lot of explosions. The singularity/energy drain combo gives you the option to take your distance from tough boss units - though as always in ME - you could also charge into most of them with the right timing.

After playing that way and always going into the face of enemies with charge I was surprised how well you can keep the enemy AI on distance with the second build. Tech explosions for crowd control/boss units and glorious sniping shootouts (the Kett command centers or in general Kett buildings where you can take those bastards away one after another with the Isharay were the most fun) meant a more tactical/composed Ryder.

Build three was the total contrast again and is definitely the most powerful build among the three. A lot more squishy than the first two, but once you level up the passives, it really becomes an OP build. Lance has an evolution where it doesn't have a cooldown (but strips your shields which you can build up with energy drain again), so it's going near the enemies, once they are in your annihilation field (which has a pretty wide radius when you leveled up) you throw lance at them for a biotic explosion and then shoot them in the face with the shotgun. Enemies going down left and right in seconds is the result. Pretty satisfying gameplay. 

I absolutely love singularity and charge (which is why I played that style for parts of three runs), but have to say that both of the others (which I played in 1.5 and 1 of the 5 runs so far) are as much fun for me. If I play a sixth run I might stay with the third style for some more time before trying the next build.

This was my first play through, used those 3 all game because it was just SO much fun, rag dolling Kett and the maxed out biotic explosions? It's amazing.

I tried a few play styles. Engineer with turrets, Infiltrator sniper, vanguard biotic God. All are pretty fun, but my favorite is Infiltrator sniper. That's my main in any rpg where it's possible. I did the class in DAI with cloak because that's how I roll.

It's one reason why I prefer the old class system.  Most playthroughs feel the same now no matter what you start out as.

In my latest game, I'm forcing myself not to play a sniper infiltrator, which is my favorite...I'm playing an assault rifle engineer, mostly using three tech skills. Switching profiles doesn't work well for me...they don't seem to stick properly so I'll find I'm not using what I thought I was using, sometimes leading to being dead.

My first playthrough used two different playstyles. I started an insanity on NG+ and abandoned it because of the enemy scaling. #2, the Infiltrator, was a new start and I left aside some xp so I wouldn't encounter too much of the bulletsponge.

The one that makes the least usage of cover.

I only did SP for 75% or so back in March and then focused on MP, so through all these kits, I have forgotten exactly what powers I ran.

I do remember I had a Biotic and a Tech profile, one Vanguardish and I think I was fiddling around to see if I could create a Combat profile as well. It was all still trying out, though.

I'm now doing my second playthru on Insane and started out with Sentinel: Energy Drain, Throw and Invasion. I'm building a second profile with Adept: Pull, Throw and Singularity (although I may trade it for Shockwave) and still plan to do a Tech and Combat Profile.

But I'm currently only around level 25, so I haven't been able to spend that many points. I'm now getting some points invested in Pistols and Sniper Rifles, so will change the Sentinel to Explorer, I think...

Remnant VI & Assault Turret is a lot of fun since you can AFK and do something else