I'm not participating in the contest, but will throw in my 2 cents

haven't seen many dating survey FA threads in this contest, but I'm currently running one on
PropellerAds classic push traffic with somewhat stable $0.20-0.25/day profit and total $7 profit for the 2.5 month lifetime of the campaign LOL more for fun of course. I might be misinterpreting, while contest focuses mostly on pops, from contest description pops do not look like a must (based on suggestion to try different
traffic sources), so push could be worth a try.
A couple of GEOs to try were suggested by
Zeydoo AM, in-page push campaigns died out quickly. Last remaining classic push campaign runs on high activity users 1/day, never changed creatives for the whole 2.5 months. Initially added a couple of prelanders (survey and chat), but after struggling for some time my (defective?) ML backend decided that Zeydoo dating survey offer (2061) performs better without them (outperformed by about 10%). Stats attached.
WIth direct linking it's mostly about careful bidding, so CPA could do the trick.