I won't spend too much time on this, seeing as how the majority of commenters have already disagreed with you. But like everyone else, you're entitled to your own opinion about which of the trilogy is the best.
Psych the Psycho said:
OK, let's get this out of the way first, Mass Effect 3's ending is trash (with or without the extended cut) which already puts it below ME2, but that's not the only reason.
That's just an opinion, not proof of superiority. It's an opinion that many seem to share, but an opinion none the less.
1- In ME1 the combat was unrefined but had very good role-playing elements. In ME3 the combat was very polished but there was way too many fights and the role-playing elements became simplified to the point where there didn't seem to be any at all. ME2 on the other hand, had the balance just right; the fights never felt forced and having dialogue conversation during missions was always interesting.
If anything, I'd say ME1 had the most conversations/roleplaying options while ME2 actually had the fewest. With regards to ME3, of course there's going to be a lot of combat. For one: the combat was finally perfected beyond ME1's "run in with guns blazing and hope you've got someone with Singularity or Lift on your team" and ME'2 "Just make sure you've got someone with Overload and someone with Warp." Beyond that: the Reaper War has officially begun, the entire galaxy is under attack...did you expect you'd just be able to walk from one plot point to the next?
There really isn't much roleplaying in ME2 other than "Do you want to sound like a dick in this conversation or not?" But then again, the same can be said about the entire trilogy. So looking at the "big choices", really the only one of any significance is whether or not you're going to blow up the Collector Base.
2- ME1 let's you explore each planet you find, though most were barren, the main hub world is the Citadel, this is the same for ME3 but on a smaller scale which causes it to get boring after a while. ME2 however didn't have one hub world but four: The Citadel, Omega, Illium and Tuchanka, all of which had plenty of stuff to do.
While ME2 was the only one that really had "Hub Worlds" in the traditional sense (though technically Rannoch and Tuchanka would count in ME3), the hub worlds weren't really that great. In the ME series, I'd argue that the Normandy is your "hub world", allowing you to explore all the various bits of the galaxy.
With regards to ME2's Citadel and Tuchanka, the only reason you HAVE to go to those places are for two loyalty missions each...not exactly shining examples of hub worlds. Omega has a loyalty mission and 2 character recruits while Illium has 2 recruits and 2 loyalty missions, so it's the hubbiest of the hub worlds. But again, for a series like Mass Effect, your ship is your true hub.
3- Throughout the course of ME2, there is constant build up to the final mission and making sure everything and everyone was ready for it. ME1 was more about finding and stopping Saren which did have so tension to it but not a lot. In ME3, the first half did have some build up to the final push but after craving through tons of enemies the game starts losing tension.
While the looming Suicide Mission in ME2 does add more tension than chasing down a rogue Spectre that you only see at the very beginning and the very end of the game in ME1, retaking Earth builds up just as much tension. You're going to lead a charge against the bulk of the Reaper armada against which your chances of coming out on top are slim to none. You finally land on Earth and have to make a ground assault against the very core of the Reaper's forces. By all accounts this is, itself, a suicide mission from start to finish.
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Beyond that there's way more categories to judge the series on than the three you picked. In fact, I'd say "better hub worlds" isn't really even a category that should be in this discussion while "better tension" is just a subcategory of "best story". You mention roleplaying but if you're going to do that then the combat itself should be another category. Some would argue that weapon selection and the level up system should also be judged. Final Boss Fight should be tossed in there as well.
In short: you kinda walked into a trap with this topic. Most people around here didn't like ME2 as much as you clearly did. Personally I enjoyed all three games of the series about the same, each one having it's pros and cons. But between the weapon selection being watered down, the incredibly forced "You're with Cerberus now" story, the level up system being watered down, and the fact that nothing really happens in the game, most people would (and apparently have, judging by the other comments in this thread) argue that ME2 was not the best of the bunch.
