
They're all safe. You only need to give Milbemax monthly if you're concerned about lung worms? Are they in your area and do your dogs eat grass that slugs may have been on? If not then usually 3 monthly or even 6 monthly worming is fine.
Advocate doesn't kill ticks, do you have foxes, deer or farm animals in the areas you walk?
I use bravecto for ticks (it also kills fleas but I wouldn't bother with that on it's own) and either milbemaxm, drontal or cestem for 3 monthly worming.