Hello, would you please name in your opinion the best compound exercises for these muscle days?:

back/bicep/forarm

pec/tricep/delt/trap

leg/ab

Thanks!

or if you know some really good ones that don't fit into those 3 muscle days, would you please name them anyway? thank you!

Not sure if I really like "muscle days" but I do like compound exercises. I have been working a little on a routine building article, but it is on my work computer and I have been busy there, so progress is slow.

I am just going to list a few of my favorite exercises.
Overhead Squats - core/legs/shoulders - very difficult, very frustrating
Push Press - shoulders/triceps/legs
Deadlift - lower back/hamstrings/glutes/traps
Dips - triceps/chest
Squat - quad/glute/hamstring
Pullup - back/biceps
Row - back/biceps
Bench - chest/triceps
Woodchoppers

Here's the "Big 5" which are all the best compound exercises that should be in all routines:

Full Squats
Deadlifts (regular, stiff-legged, romanian, etc)
Pull-ups (or chin-ups)
Bench Press (flat or slight incline)
Dips (not bench dips, since they are primarily tricep only)

I would also suggest these two for balancing the workout:
Rows (bent over barbell kind)
Shoulder Press

Here's a sample workout that will work well for strength and size gains:

All are 3 sets x 8 reps, try to do it every other day:

Day 1:
Full Squats
Romanian Deadlifts
Pullups

Day 2:
Bench Press
Rows
Shoulder Press
Dips

You can mix and match, but I would limit yourself to a max of 15 sets per day (like doing the Big 5 3 times per week). You can add optional ab work at the end of day 1 since its only 9 sets.

Thank you! I will try these! my old routines had 24 sets per day 3 days a week, lol.