I've asked a similar question back on the MT section but wasn't sure if it really belongs there so I'll ask here in more details. I'm debating on what to use the potentially next MT on (already use one at the start of the account to get Amaterasu).

Fire SSR: Ares (AW), Mars, Prometheus, Amaterasu | Fire Eidolon: Belial LB1
Thunder SSR: Mammon, Brahma, Tyr, Dian Cecht, Justitia | Thunder Eidolon: Girimehkala LB0/Ouroboros LB0
Water SSR: Nike U, Poseidon, SA Raphael | Water Eidolon: Tiamat MLB
Wind SSR: Titania, Hastur | Wind Eidolon: Hraesvelgr LB0
Light SSR: Atum, Shamash, Takeminakata | Light Eidolon: Behemoth LB1
Dark SSR: Pluto | Dark Eidolon: Echidna LB1

Thus far, I can cross out dark. I don't seem to have too many core SSR on light and my eidolon appears average so that can be ignore unless what SSR I have are good. That leaves the four main elements. Fire I was debating on as it's currently my strongest at 45k power. Based on a lot of posts made, Svarog should be the priority to get then Urial. However, I'm debating if with the next MT I should get her or hold off and supplement my other teams? Thunder is my second best at the moment as I am trying to get the weapon grid ready for upcoming water union (92% assault with 4% extra from one pride so 96% total), but I doubt the next MT will be before water so ignoring any water events, should I get another SSR for thunder to compliment my fire team? I notice I have some decent core water SSRs, but I don't know if I should continue with it. The only reason I can think of is to better handle Fire Ult raids to gather more materials for fire soul weapons. And lastly would be wind which is underdeveloped in terms of weapon grids, but I was lucky and manage to pull another 100% eidolon. I thought about investing in wind because of pulling Hraesvelgr, but being my weakest of the four at the moment, I can't decide on what to do.

So to attempt to shorten this, should I get Svarog to finalize fire, another core thunder SSR to match my fire squad in strength, a core water SSR to make a full 4 girl SSR to battle Fire Ult easier, or a core wind SSR to start building my other 100% eidolon team. Sorry for the long post and thanks for advice in advance given.