I have been playing the server for a long time and have been noticing that the rare and mythic crates are never used and the common and uncommon crate are hardly used. My suggestion is to add a way to obtain the higher tier keys (such as a custom mob drop) and completely redo what each of the crates may give you as a reward. I just don't see the reason right now why anyone would bother going for an uncommon crate as it's barely better than the vote crate.
Keys could also be obtained by new minigames as well! Server really needs stuff to do for residents of towns.