I subscribe to Rodale's Scuba Diving, Sport Diver, Alert Diver, Northeast Dive News. All are good for what they are for. The first two are basically pretty picture magazines designed to get you happy about diving. One also has a bunch of PADI adds, but surprisingly they are not that obnoxious.
Alert Diver is one of my favorites, can be very informative, but sometimes also very dry. Northeast Dive news talks about diving around here.
I used to have a subscription to Undercurrent, but it is very expensive and I found I was not reading too many articles as they were mostly resort reviews.
I had Dive Training but let my subscription lapse. It was a good magazine and I might pick it up again, but honestly how many subscriptions can you manage?
Ive read a few others over the years. Some were good, most were bad, it seems that they are all out of publication now.
Dive shows are a good place to find new magazines and get freebies.