Both tyres are good. I currently have a set of the Goodyear ASY 3 on my 18’s and have the Michelin PS4S on my 19’s. Both drive well, both feel confident in all weather conditions and so far seem to wear evenly and are lasting.
I suspect the Michelins will offer a little more ultimate grip at the higher end of the performance scale vs a trade off in overall life span and ofcourse price. But thats not to take anything away from the Goodyears as I like them alot.
As a comparison I had a set of OEM Pirelli tyres on the 19’s before the Michelin PS4S and I couldnt get them off faster enough. I could not find any confidence in them at all, especially in the wet.
One final thing to note is side wall alloy protection. The Goodyear ASY3 offer very little protection ( on the 18’s atleast ), certianly compared to the Goodyear ASY 2’s , where as the Michelin and the Pirelli both offer decent overhang, albeit in different shapes. Michelin is square where as Pirelli is at an angle.
There is a thread on tyres and protection if you search for it.
Here
http://www.audi-sport.net/xf/threads/new-tyres.254513/page-4
Hope that helps
Jungle