Low-hanging fruit for sorting mechanism: sort by a combination of activity and voting power. E.g. voting on >90% proposals actively will rank a delegate with 0.1M OP higher than one voting <70% but with 2M OP
A more abstract but long-term idea: delegate discovery rewards. I.e. if you are early to delegate to someone with 0.1M OP delegated, promote them, and they make it to 1M or 2M OP or whatever, you get a reward. The earlier you find them, and the bigger they get, the more your reward. It could potentially be gamed if one has access to millions of OP, but governance could subjectively disqualify as those with millions of OP are few and very visible. This can be combined with delegation rewards (which is much more important right now, given the very low participation of stake even for well known delegates) we had discussed earlier to further decrease the possibility of gaming it.