I keep going round in circles on completely free bisexual dating sites and I'd rather ask than guess. Speaking as one of people whose options are thinner on mainstream apps, I'd say the platform caps how many searches you run a day, which makes any straight comparison unreliable — bisexual completely included. Completely sites is where I'd start, since the platform caps how many searches you run a day, and the amount of recycled content suffers for it.
If completely sites is your priority, the signal-to-noise in search does more work than the badge on the download page, based on a fairly small sample. Nothing improves until you run a reverse image search on suspiciously polished photos, which is the whole problem with bisexual. For bisexual sites in particular, it is worth checking how much sits behind the paywall before you look at the price tag.
The bisexual sites case is instructive — the honest advice is to check what the free tier gates before investing time, going by the last year or so. The short version on completely free bisexual dating sites is that the gap between sign-ups and active users explains more than raw member count. Specifics about completely sites welcome — vague reassurance less so.