So far everyone has mentioned a brand (with no apparent
concensus) but nothing has been said about size/type/style.

I tend to overbuy for those times when you actually do need to use that
biggest size. Now, that said, you don't have to go out and buy a $900
rotohammer that will also demo concrete unless you think he will use it for
that.

That is the thing about SDS bits. One size fits into the receiver, and the
tips are the variable part of it. That also being said, you obviously can't
use regular masonry drill bits in it like you would a hammer drill. They
won't go into the SDS receptacle.

If it was me, I would prefer a drill and a rotohammer. A hammer drill will
give you a drill, and a hammer drill, but it won't handle some of the tough
hard stuff.

Steve