i'm thinking of doing the 5X5. real simple and straightforward.
strength and muscle mass are wanted here!
what kind of variation?
5x5 is ok but can also lead to little response for people. Not everyone will work well in that rep threshold. Also the load can put too much on someone and chronic issues may develop.
I personally would consider a rotational, hybrid Westside Barbell scheme.
MAKE THE PROGRAM WORK FOR YOU AND YOUR GOALS.