Don't really have a single favorite non-Mopar, but there are a few I like:

Ford/Mercury:

Mustang fastbacks and the 69-70 Shelby GT350/GT500 always looked nice to me.
66-67 Fairlane
64 T-bolt factory drag cars
Some of the early Mercury Comets and Cougars look nice when done right. Ronnie Sox raced a Comet at one point.

GM:

55-57 Chevy as early day 2 race cars or hot rods only. Stock they are boring as can be. Also don't care for the convertibles of these either for some reason.
61-62 GM "Bubbletop" cars are styled nice. Good freeway cruisers that still turn heads
62-67 Chevy II - Not the best factory brakes or suspension setups, but plenty of go fast potential with the right engines
66-67 Chevelle
66-67 Skylark/GS
70 Buick GSX
Some early GTO's are ok in my book.