I am about to put concrete sealer on a driveway and inside a garage. What sealer should I apply, if I am specifically interested in preventing water from getting in cracks and causing frost heaves and less interested in aesthetics? Brand recommendations, as well as types (e.g., epoxy, silicates) are welcome.
Epoxy is not light stable (ie: it will discolor) and silicates are densifiers, but do not seal concrete. It's likely that you have a broom finished driveway and machine trowelled garage, so whatever chemistry you use needs to be compatible with both types. Most film formers (acrylic, epoxy, urethane, etc) will require an acid etching (at minimum) for proper adhesion on trowelled substrates. Though film formers are usually preferred for their aesthetic qualities, and you've said that aesthetics aren't that important.
Bottom line is, I would recommend a penetrating sealer; either silane or siloxane. You'll get maximum protection from freeze/thaw damage and deicing chemicals, and good longevity (about 7 years outdoors, 10 in the garage). ChemMasters offers silanes with 40 % to 100 % active ingredients (Aquanil Plus 40, 55 or 100). These are solvent-based products, and you may find the solvent fumes overwhelming when used in an enclosed area like a garage. Spallguard WB is water-based (no solvent fumes) with 10 % active siloxane (siloxane is a larger molecule and requires fewer actives to seal concrete). This may be a better choice for you.
*Please note that I am affiliated with ChemMasters (link in profile) and there might be similar products available from other vendors *