We can't help you with this question--it's up to you. A good instructor will not favor anyone despite personal feelings, they will set that aside and give features to the most deserving person. If you've been in colorguard the past two years, this tells me that the instructor obviously thinks you're a good performer when they choose you to be on the team--are you sure the instructor's feelings are getting in the way, or are you making excuses for not getting "feature" parts?
How do you know the instructor does not like you? Do you have proof? Don't immediately assume something because you're not getting what you want.
If you do have proof, an instructor can get in serious trouble for letting personal feelings get in the way of their teaching.
If you love being in guard enough, whether or not you like the instructor shouldn't matter. If you're letting the instructor get in the way of your decision to join, you're cheating yourself.
The decision is up to you--but don't be quick to blame someone when you don't get what you want.