Crobat is very useful in-game, possibly more so than Pidgeot. However, the only way to evolve from Golbat to Crobat is through levelling with max happiness (haircuts, vitamins, EV berries, etc) whereas Pidgeot is a standard level-based evolution. It will take more effort, unless you can make do with Golbat.
Since you're playing HG, I'd also recommend Crobat as it can (along with pre-evs) learn both Mean Look and Taunt, which can be useful when going after the roaming legendaries. Both can learn Fly at first evolutionary form. Crobat's typing suffers an additional Psychic-type weakness but gains extra resistance to Grass and Fighting-type moves, and its movepool is better.