Observation from PitMad: Comp titles serve different functions in queries versus pitch contests.

In a query, comp titles demonstrate that you know the market and show your book's niche. They should be recent, not ultra-famous, and in your medium, genre, and age category. For example, I compared AMONG THE RED STARS to CODE NAME VERITY and FLYGIRL.

In a pitch, though, all that goes out the window and the only goal is to make agents go "OMG, that sounds awesome!"

So, for example, "my magical YA space Western is FIREFLY meets THE WIZARD OF OZ" would be lousy query comps. They're old, they're movies and TV, and they're not YA. They demonstrate nothing about your market knowledge. But they would probably make an agent smash the LIKE button.

My recommendation: Have two sets of comps, one closely realistic set that demonstrates your market knowledge and one fun set that can be as wild and eye-catching as you like. You can also mix and match. This gives you the flexibility to describe your book different ways.