ME3 certainly had hands-down the best class and combat mechanics. ME1 was just barely half-finished and the loot management (and loot!) was just crap.
At least ME1 had loot.
All the games had loot. The loot's contents just changed throughout the series
ME1: Weapons, armor, and mods. Shame that the vast majority of it was stats-wise basically identical, and very little of it was anything other than a different color. And you got so friggin much of it. And often times it was never what you actually needed, like upgraded armor for your alien crew.
ME2: Resources for upgrades, occasionally actual upgrades, and rarely new weapons. All of it important, but very linear. The new weapons you find are almost always straight-up superior to older versions rather than sidegrades (with possible exception for the heavy weapons).
ME3: Ah, the pinnacle. Lots of upgrades and mods, and the weapons you collect are designed in such a way that none of them feel straight-up better than the rest. At the same time, they are also different enough that your weapon selection plays a large role in the way you play the game. And you get so many of them to play around with!
