Unless you have some tight spots to get into, go for a larger diameter bit and 1/2 inch shank. The larger diameter is good for avoiding chip-out as well as curing deflection problems. Get the 2" length because one day you'll need it.
“We should be careful to get out of an experience only the wisdom that is in it and stop there lest we be like the cat that sits down on a hot stove lid. She will never sit down on a hot stove lid again and that is well but also she will never sit down on a cold one anymore.” - Mark Twain