Was Tali and Miranda more often than not.

Usually I swapped them out, but the only characters I really loved were Garrus, Thane and Tali. Miranda was a dumb sex-bot that I just loathed even looking at. Jacob was a for-hire, Jack was messed up. Mordin was alright, Legion would have been cool if I could have gotten to see more of him. And the only reason I didn't roll with Grunt more is the fact that he reminded me of Wrex, which I loved, so Grunt could never really live up to Wrex.

I actually tried to not use any two characters more than anyone else so I got mostly even spread with all my characters. The only two who were used less often were Jacob and Thane but not by much.

It's been a while since I played, but I remember using Tali and Legion a lot; very interesting characters, and as a Sentinel I just tanked everything and essentially had 4 other members shooting at the bad guys, what with their drones. Thane was also amazing and had a great story arc. I didn't play the first ME, so Grunt was very enjoyable without knowing who Wrex was.

The characters I didn't use? I really wish Jack and Miranda's skillsets were switched; Jack was my romance option and I liked her "badass on the inside, vulnerable hot chick on the inside" personality.

Miranda just seemed to be too much of a rigid bitch, but I brought her along every now and then because Overload + Warp is great to have. Mordin seemed kinda "meh" as far as story went, plus he's a scientist, not a fighter. Jacob seemed very cliched (bottled up soldier with a typical past). Garrus...seemed kinda boring too and just thrown in the game for nostalgia. Kasume = DLC squad member = no interaction in the main story. Samara was so boring and lame I didn't even do her Loyalty mission.

I'd always have Miranda no matter what with either Grunt or Garrus as a sidekick. Mostly Garrus though.

First game Garrus/Wrex 24/7.

I was the tank so I mostly played with Mirana and Tali/Legion.

Thane and Tali, but I switched things up quite a lot. I started using Kasumi a lot when she was added, she was a great character and it's hard not to love Garrus.

The only character I really didn't like was Jacob, he had zero personality.

Miranda + another biotic

Either Jack/Thane or Samara.

Miranda and Grunt, they had the most useful buffs for insanity run

I rolled with mostly Grunt/legion long-mid to mid-short range, sometimes I would change it up but those were my main two

In the 4 times or so I've beaten the game I probably rollled with Mordin and Grunt the most. I really liked Thane and Legion as well and used them quite a bit too.

Garrus and Jack. 

Thane and Legion for a big majority of the game.

I tried to use appropriate character depending on the enemy we would face ... Blue Suns? Overload! ... Collectors? Warp! and so on ... so I switched quite a lot. I used Miranda often though.

Mordin and Miranda

I used Garrus most of the time. Thane and Samara makes the last mission super easy even on Insanity.

I stuck with Miranda and Mordin so I had options to deal with nearly every enemy type. Their incinerate and warp, combined with my range of ammo types from playing a soldier, made the insanity playthrough a cinch.

When I played as a Female Shepard, I chose to side with Morinth near the climax of the game, and I thought she was surprisingly powerful. I did have to kill Samara though, which was not a fun choice to make, but it was my decision.

But other than that, Garrus, Grunt, and Mordin were my favorite teamates.

In my own mind I was AFRAID that I needed to rotate people on and off the missions, so I tried to bring everyone on at least a few planet fall side missions to "train them up". That was not the case so it wasn't an issue...but that was how my mind worked. The interesting thing about the games structure was that getting your team and then doing their loyalty missions meant you DID have to play most characterless at least twice times.

When given a chocie, I woudl bring Miranda instead of Samara. And, I would often bring Mordin or Kasumi instead of Jacob. However, I tended to bring Zaeed instead of Garrus which is probably what most people who not have done. I liked Zaeed's rough attitude and his war stories, and I often felt Garrus was too prissy.