RT-AC87U or AC3200 or AC68U or AC68P

I want to add a router in my bed room to get better signal there. My walls are old plaster with wire mesh so signal isn't good there. Right now I have an RT-AC68U so I was thinking of upgrading that one and putting the AC68 in my bed room.

I was going to get an AC87U but have read a lot of bad reviews on that one. Are the reviews true?

Would an AC87U or AC3200 simply be overkill?

Should I just get a second AC68U and if so, should I get an AC68P?