My Browning A-Bolt wears an EGW Aluminum Picatinny 1-piece base. I chose that base because 1, it's aluminum which is weather resistance, and 2, 1-piece which is strength. I also originally bought the Burris Ex. Tac. Rings (again, aluminum and beefy) Medium height but they were at LEAST 1/4" too high as that combination left about 1/2" of clearance. My lady bought for me for Christmas the Burris Ex. Tac. Low rings which are perfect for my rifle/base/scope. Now I have about 1/4" of clearance between the objective and the barrel, minus a little bit for the scope cover.
In terms of strength + weather resistance, 1-piece, aluminum (if possible) and beefy. As others have posted, a hunting rifle takes a bit more abuse than rifles intended for mostly range/plinking use, so "extra" strength is definitely a plus. Integrity to Spare...