Wizard Slayer is a cool concept with a bunch of unique features. His ability kit would be strong, it just doesn't have enough numbers to compensate for the disadvantages (unlike, say, Berserker).
Meanwhile Beastmaster is just dumb and I see it as an "afterthought" since all the other Ranger kits fit certain niches and Beastmaster is just... there. Even if you could salvage him, why would you want to (while still retaining the concept)? Might as well make a new class altogether.