Old Overholt is a solid mixer, but I'm not sure I'd drink it straight.
I keep a bottle on hand for Manhattan's, but it's not first choice. Rittenhouse is also a solid mixer for Manhattan's. Maybe a step above Overholt. Overholt is a great deal for the price, though. Both of these tend to sell out IME.
If I'm not mixing it, I'd rather have something like Russel's Reserve, Sazerac, or something along those lines.
Bulliet Rye makes a very nice Manhattan.