Which healer to use until Endwalker and Sage?

[Sunhwapark]

It's worth giving them all a try, it would give you a good opportunity to learn more about each individual skillset and how they function in a full-party+ setting.

until lvl 80 stuff with seraph whom Idk them shields is as just as low as succor.

Deployment Tactics is far stronger with Adloqium because the potency is much higher than succor.
Seraph's AOE applies an Adloqium strength shield on everyone in range and can be applied twice during the ~20s summoning window, their single target spamable one is weaker though.
Basically everything is better than having to cast succor, including Sacred Soil.