Any opinions?
I would post your question on http://www.mirafiori.com/ and www.digest.net and see what responses you get from owners. First thoughts would be that the ALFA is a little less prone to rust and somewhat more sturdy. Also parts will be pretty much exactly 2X the cost. It's just the rule of ALFA vs FIAT in general.
between those two i'd be going for the 124. for an alfa i wouldn't look past the 105 series, love those things.