Watch out with many of the larger tetras as they can be nippy. Congos and Serpae get large but I would worry about them. Emporers, Penguins, Head and Tail Light and probably lemons and Silver Tips should be fine once they reach adult size. If the angels are small then now is the time to add the tetras you want so they have time to grow up.
Neons are pretty small. Most other tetras can get to a resonable size and hopefully will be fine. I would provide cover and a decent size school for safety though.
red/blue columbian tetras are one of my personal favorites and they get very large (also do not nip). emperors are sexy too although i have never kept those. I assume they do not nip either.
i raised my angels with 5 head and tail light tetras (~1.5 inches), and never had a problem, now the angel is large and all but 2 of the head and tail lights have died, so the other day i added 2 baby harlequin rasboras. the angel has given them no grief and they are very peaceful towards him and the other tetras. so in my experience, if you raise the angels with medium size tetras, they will get along with them and any new ones you add later. i don't think you need to go as large as emporor tetras if you don't want to, pretty much anything except for baby neons should work.