best bases and why varies depends on what you believe..
some folks like a steel base mounting to a steel receiver as they feel that they are same metals and expansion characteristics ...
look for offerings from warne tactical and others..
others don't see a problem using a aluminum base with a steel receiver..
look for offerings from evolution gun works (egw guns) among others..
same views as far as ring construction..apply..
aluminum rings on aluminum base, vs steel rings on steel base..
I had a warne 0 moa base and it was solid, but I needed a 20 moa base and
put a EGW one on i have been happy with it..and IOR lightweight rings
so I'm not going to say what's best.. just tossing different views out..
limiting factor in my mind is no matter what base, the mounting screws can only take so much torque anyway.