My thing on masks is just to make sure that they fit well. Try on as many masks as you can and go with the one that fits the best. I'm on my third mask and have finally found one that fits perfectly. I harldy ever have any problems with leaks (if it does leak my snorkel is usually the culprit). When I did the little test of holding your breathe and seeing if the mask stayed on, I chose the one that was the hardest to pull off. I had just purchaed a very nice high end mask just a few weeks before this mask, but it was driving me crazy leaking all the time. The mask I have ended up with is some cheap off brand, but it fits perfectly.
As far as the fins, you'll hear people being adament that split fins are the best and others saying that you shouldn't get split fins. Personally I LOVE my Scubapro twin jet max fins. I purchased them back in Nov. and unfortunatlly lost them a couple of months ago. I never even thought to purchase a different fin. I went right away to buy the exact same pair again. A friend of mine just yesterday switched to the twin jet max fins and couldn't stop talking today on the boat about how much easier they were than her previous fins.
It is all about personal preference.