For weight balance v power. The best block is a c16xe. As these can be tuned up to c20xe level (budget pending).
However, a 1.8 bottom with a 1.6 head works well too
but if you want power and then have to adjust driving style, a c20xe is great fun out of the packet, but then a let puts you right up there
as others said, small block v big block argument.
dan (old admin) had a really well set up 1.6 8v. Ben had a 1.4 8v on 40's that went really well and cp has a really good spec'd 1.4 16v and all these are some of the best handling cars I've been in/seen.
Personaly I think it's
Handling v power argument.