What would make ranked feel fair?

There's no ladder yet. If one gets built, I'd like it shaped by what you expect rather than what I guess.

The questions I keep going back and forth on:

• Seasons with resets, or one rating forever?
• Should faction choice be locked in, or random allowed?
• A fixed map pool, or anything goes?
• What should happen to your rating when someone leaves a team game early?

Answer any of those. Or the one I'd find most useful: what annoyed you about ranked in other RTS games?