From over a decade of reading, I can say that every Ordinal voting system is exploitable in un-democratic ways.
Arrow's Impossibility Theorum is the main thing to know here.
Cardinal Voting systems are better, but not completely flaw free.
I personally like either Approval (simple but less responsive than it could be) or STAR, which is responsive but more complex.
If I wasn't on my phone I'd link the electowiki that site has great breakdowns of different systems.