Originally Posted by
Sindeloke
I've been playing around with the idea of "you can add one fixed integer and one die roll." So you can have flash of genius and bless on the same roll, but not bless and bardic inspiration, and not flash of genius and aura of protection. It's not as flexible as your "pick any two," but it'd very easy to track. Apart from preserving bounded accuracy, it would theoretically also encourage spreading buffs around.
You'd probably have to do something like 3.path did and give them explicit nonstacking types, though (static and rolled, or w/e). You don't want to be unclear about whether something like Archery Style counts as a fixed integer bonus, or whether shield stacks with a shield. (If things like Archery and shields did count, though, that would help to address certain other concerns you sometimes see on this board.)