I go steel when I can, and either way I get a base with a recoil lug integral to it if there is one made for that receiver. Nightforce rails on most of my stuff, steel with the recoil lug. I bed them with JB Weld too, make sure they are dead flat and no stress or twisting/distortion when torqued down. Most if not all production receivers aren't true and the rail will be distorted when you torque it down, a quick check with a machinists square has shown me that. I have sent a couple rails back for exchange too, they aren't straight and flat out of the package.
I have aluminum rails and have had zero issues, ever, but for an ounce or maybe 3 why not steel? Every time I order a rail I ask myself that question and I can't come up with a compelling reason to not get steel. Maybe one day I will build a super light something and have a reason.....
All of my pic rail rings are aluminum, I have some steel rings on two piece setups like the Leupold dual dovetail etc, but I use heavy aluminum rings on everything else. 4 screws for the cap and 2 for the base minimum for me. Every one is at least advertised as a 'matched' set of rings too, does no good to have a flat and straight rail and torque the tube by using rings that aren't also true.
Is my way overkill? Yeah probably so in 99.999% of what I am doing but I don't wonder if my stuff is going to hold up.....