I preferred the gunplay of ME1.
For me, the stat based aiming didn't help much as you couldn't make a non sniper rifle very accurate even with high accuracy rating. The targeting circle only got so small and at some point accuracy rating stopped meaning much and I just had to accept that the game was going to arbitrarily decide I missed x% of my shots.
I know it's standard for a RPG to use RNG to hit, but it's never been a mechanic that sat well with me in a game where I'm also expected to manually aim the weapon before I get a shot at the RNG.
The Sniper Rifle went the other way entirely and was always pin point which effectively made it a skill based weapon where the accuracy stat made it require less skill to use in the form of making it less wobbly.
Plus the fact that every weapon in a class might as well be the same damn weapon with the damage number adjusted didn't help. The game feels like it only actually has 4 guns, which Mass Effect 3 hit on a nice variety even if the balance of them is off.
and while it's still one of my favourite games of all time I am going to fault it for that. If you include the option to use real time shooting then I'm going to criticize it if it feels clunky.
I did actually like the heat mechanic though. It just needed some balance so that certain weapons didn't have near infinite heat.