yeah, I would prioritize Gaines

Robinson is a very good run defender. But while Gaines is not a pass rusher he can get to the QB more than AR (9 sacks vs 2 the past 3 seasons). I think he's a more well-rounded DT, no pun intended. Run-defending DTs are easier to find and Brown might be on the cusp.

Just a year younger but again that's another reason I would try to retain him.