I've always had MK2's, 8v's and a 16v, drove a Vr6 swap once and loved it. MK1's are lighter older a little more rare. Probably easier to find parts for the MK2's. You can pretty much put whatever motor (16v,1.8T,2.0T, VR6) in whatever car you want.
I did have a 1983 MK1 GTI briefly, bought it from a towing auction for $5, it had been rolled and must have landed upside down. Trailered it to work, picked it up with a forklift by the roof, to un-accordian it, got the door open, un-hydrolocked it and tossed a battery and fuel in it and got it running! Would have loved to keep it because of the older more square, but the body was beyond repair.
I think either car would be a fun project, I would be open to either if I didn't have one. I would look for something without rust, either something stockish, or modified close to what you are looking for.