The two I liked best were Volatilegaz's list and Fenris' list.
Quite a few people in this competition noticed that DAs are actually priced appropriately in PL even if they aren't in points, and ran DA-based mech lists. Fenris' seems very close to optimal, with lots of small squads of DAs with kitted-out exarchs, exactly filling 3 Wave Serpents with an AT-ish loadout and very good HQs (including an Ynnarri HQ) to buff them up. It's a very fun list making use of a unit that, in points-cost play, is not very effective.
Volatilegaz' list is a lot less interesting in comparison, in that it is also a good list in points values. Mechanized Wraithguard, 2 squads with D-scythes, 1 with Wraithcannons, a Hemlock, and Yvraine. You could easily see this in a tournament. However, I think the list is very tight and would be highly effective. Wraithguard are excellent, Serpents are excellent, Hemlock and Yvraine are both great.