Most Usefull Research Path...

[Shovah32]

Well it doesn't require a mage with S9, it brings a group of weaker angels that can be used as blockers and it brings the Seraph in as a commander - meaning no Gift of Reason is required.
Not too odd.

[sum1lost]

And you can GoR the harbringers for some more good commanders.

[Frostmourne27]

Marignon also gets the angel summons, both in Mid and Late. Late Marignon has acccess ot about a zillion awesome summons - all of blood and some crazy nationals, not to mention Fallen Angels from reascendance.