We use "by a long shot" for comparisons: I like to play golf and tennis, but if I had to choose just one, it would be tennis by a long shot.
B. I love to play tennis a great deal.
This is a correct, but "a great deal" doesn't work so well with "love" for me -- if you love it, you love it. You don't love it a little, or love it a lot (even though you hear those). So I would just use "I love to play tennis."