Did you mean a 312 or 351? The 320 is a GMT of course. I owned a 312 when they were new last year. It's nice but the 351 i bought recently blows it away imo. Ti/brown dial/gold hands beats a steel case, black dials and silver hands every day, imo.
So, of your nominations, the 351 by a very large margin and rather cheaper than a 320 too.
Have you seen the 386 due to be launched next year? Better than a 351 in many respects, though a while to wait before they hit the streets.
http://blog.perpetuelle.com/index.php/l ... e-pam-386/