I personally don't like Leupold bases. I've had them work loose on me in the past and the ones with the double dovetail system are hard to get aligned just right. And their standard system (not the dual dovetail) with the rear ring held by windage adjustment screws just begs to shift under heavy recoil. That system is just plain poor.

Talley rings are best in my book. They're expensive for a reason. Those things are rock solid.

As for bases, fewer parts are better, starting with zero. My favorite system is Talley rings on a Picatinny or Weaver rail that is integral to the rifle, or model-specific Talley ringmounts onto a rifle's proprietary rail. Next best is a Talley Picatinny base that screws securely onto the rifle paired with Talley rings.

Don't buy any damned two piece base systems from other companies. Why introduce another source of working loose or misalignment into the system?