I don't play ranked often, but I do like splat zones the mosts. Tower Control is pretty good as well, but I think the tower's center area looks weird on Blackbelly Skate Park just because it starts off way above ground level. Rainmaker is the worst though. You can't use specials while holding the rainmaker and it is impossible to splat anyone with the rainmaker unless you fully charge it. That mode is just more annoying than fun.
Tower control is my fav because #Bucketmasterrace. Splatzone is good for snipers sometimes if the map is good. Rainmaker is just painful and hard to play and I hate it.
Idk, mine seems to change constantly.
I'm pretty good at all of them, but I've never doubted rainmaker, I'm very good at defeating the rainmaker and transporting it as far as I can, I usually can't get all the way to the base, however I get very far to a distance they can't overtake me.
I don't play Ranked much, but when I do I prefer it to be Rainmaker. I'm not sure why, but it's just the most fun to me. I also like Splat Zones okay too.