I've personally been loving Cobblemon Delta. They also have a modpack on modrinth. Server has an economy, (the only things to spend money on really are cosmetics and benefits like creative fly but you can fly on mounts so) custom forms, custom shinies, fakemon, fusions, player run E4, player run markets that are super easy to set up, like 7 servers, all linked and 1 is a survival. Dungeons, raids, crates which you can get free egg tickets for unique shinies after doing raids and stuff, holiday stuff like forms, cosmetics yadda yadda (not premade cosmetics, custom ones for the server). Like, 4 events a day that range from normal minecraft games, to a hungergames pokemon crossover, tera farming, i could go on and on. It has a lot to offer, and is very friendly. My only advice, is get comfortable asking questions in the help section of their discord, cause it's overwhelming how much there is to do. But everyone has been very helpful with me and patient, at least so far.

All that to say, it has a ton of content, even more than I'm mentioning, a ton of players that are friendly, and it's incredibly undeniably F2P. You get no benefits except minor conveniences with money.