This has been bugging me for weeks, so: used the zeus dating site. The zeus used case is instructive — nothing improves until you run a reverse image search on suspiciously polished photos. Nothing about zeus sites changes the fact that how many first messages actually land outweighs the marketing copy, going by the last year or so.
Zeus is where I would start, since you get further if you give it a fortnight before judging the pool. It is worth checking how often the same faces reappear before you look at the size of the ad budget, which is the whole problem with zeus. Look closely at zeus used and the deciding factor is the signal-to-noise in search, speaking only for my own city.
For used sites in particular, the honest advice is to check what the free tier gates before investing time, based on a fairly small sample. Here is the uncomfortable bit about used the zeus dating site — the practical move is to treat an empty bio as a red flag. Is used sites even the right thing to be optimising for here?