This is like choosing one of my balls.
Both are excellent, both have great memories, both are the sort of "first evidence" of a spanking new lineup of tried and true musicians, and both, as much as I love them, I love the follow-up even better (big fan of both Alpha and Big Penetrator).
If forced, at gunpoint, I would take Asia. I literally love EVERY song on that record, and while Sole Survivor and Heat of the Moment have a little edge, the rest of the album is almost perfect. Side two is one of the best album sides I own, and the whole record itself is in my top ten all time. 90120 is also strong, but with the novelty "Leave It" and the relatively weak "City of Love" it loses by a hair. But the highs are very high (the single I love, and "Hearts" on the first leg of that tour, with the lasers (which were retired after that leg), was something I've never seen before or since (The Firm was close) and that I'll never forget.