Need Guidance on who to Build

Hey FTP here. Been able to hoard a bit and catch up on some resources with training mats and gold thanks to the anniversary and I wanna make the most of it.

I haven't quite finished DD 7 or 8 (Mephisto & Odin) and am on the last hard nodes of the Gladiator section for Prof X. (I've heard you need to upgrade Super Skrull and some others to finish, is this accurate?)

I want to also tackle the remainder of the Annihilus Saga after these (excluding the new DD as I will likely slowly build towards GT21)

What teams do you all recommend building that are absolutely essential and will get the most bang for your buck? Seen some conflicting opinions on some stuff lately.

I know I need Vigilante and a mix of them/Nightstalkers or Sin. 6 for Gladiator. Looks like I will also need a fully built or mostly built up Hellfire Club for some of the Annihilus Saga and they may be useful for Global Villains for Prof X.

Trying to upgrade only the most useful teams. Still on the fence about Daring Warriors and Champions.

Any advice given in good faith is genuinely appreciated and I'm sure I'm not the only one...

Thanks in advance.