I say kiryu wins. mg2 goes down first because of being designed shoddily. Seriously the guy was losing in HTH with rodan. Against mg and kiryu who love close combat he'll be screwed over badly. Also to those who say mg2 armor is tough...it's not on tail swipe from godzilla and it nearly broke apart. The only reason mg2 surived so long was because godzilla kept on using his beam. The armor won't even come into play in this battle because it only absorbs attacks similar to the atomic breath. That's why the pilots were worried about rodans beam. Next to go is mg. Mg will be tough but the problem is that space titanium is really not that good of an armor. Anguirus of all people was able to break it with a grazing blow. Could you imagine what would happen to mg if kiryu did the shoulder charge? Kiryu in general has missiles that actually track making them more versatile than mgs powerful missiles. These missiles happen to be a nice counter to the shield as well due to the BIG hole in the top. Thats not even getting into the azc. Kiryu is smart enough to leap back and while mg2 and mg are trying to kill each other he could get them both. In the end I'd say kiryu's speed,HTH,better pilot,and armor will let him survive until the end, though not with out getting some armor blown up by mg.
As I've sort of casually tallied the field of opinion here, were this match up put to a vote I can tell the overwhelming favor goes to Kiryu here. I find that fascinating though it's not really unexpected. Usually it's the original incarnation of a character that tends to get the most affection, but not so this time around. I guess for a lot of people Kiryu really just hit all the right buttons.