My biggest concern with Sky Team is that their Elite Plus members (equivalent of Star Gold) cannot access lounges while flying on domestic itineraries. It might not be a concern for you (as you may not even fly on domestic itineraries), but it is something that makes me reluctant to even consider ST. Before deciding I would visit DL and Flying Blue forums - neither FF program seems to be respected very highly there.

PS> AZ now runs status match campaign - you can even be matched to the highest tier (Freccia Alata Plus) - visit forum AZ for more details...