I like the companions in 2 more than 3. Jack, Mordin, Thane, Legion, they were all very good. The new companions for 3 weren't anything special for me.

The combat in 3 is better than 2, since it is just 2's system upgraded. I also played Adept in 3 and had more fun with that than my 2's Sentinel.

The story is about a tie. I love that the entirety of 3 was a close to this epic tale and tied off all the loose ends. People hate the 'ending' but really that was just the final moments. The whole game was the ending to this series. For 2, I liked the idea of a suicide mission that relies on my recruitment and building of a cohesive team where anyone could die in the final mission solely based on my decisions. It gave me a greater sense of accomplishment to have them all survive to the end. However, the Collectors were more of a side story and I liked how 3 got back to the impending doom of the Reapers. Unfortunately, I had not played 1 at that point so I didn't truly understand the power of the Reapers and some of that was lost on me.

Overall I rate them about the same. I can see how 2 is rated higher since I think it has better companions and a more self-contained story. 3 is the end of an epic series and really requires the other two games to be played to fully enjoy it. You don't need to have played 1 to enjoy 2 (and in fact that's exactly what I did). It also helps that 2 came first, so 3 had to compare to it. Usually when there are two great but similar things the one that came first is more acclaimed since it is more groundbreaking.