I am in a similar place. I was recommended either doing one Angel by itself in my 38 or getting some and letting them pair off and doing a pair in the 38 gallon.
I was told that some members on here have kept pairs in 29 gallons so I'm assuming 30 should be fine for a single or a pair also. From what I understand if you do a pair your other stocking options are limited due to tanks space and the aggression in breeding. If you do a single angelfish I would recommend getting a larger one as the small ones seem to do better in a school. But that's just from some things I've read so take it with a grain of salt.
If you do do a single corydoras catfish are one of the most highly recommended tankmates along with bristlenose plecos where other small pleco varieties. I've seen mixed results reported on keeping smaller Tetra schools with angelfish. Some seem to have success while others don't. I have also seen recommendations that include honey gourami, and dwarf rainbow fish (though dozer recommended for 4 foot tanks or better). Leslie I have seen some examples of rasboras being kept with angelfish.
Again all of this is just from research and some replies in my own thread. I'm sure more knowledgeable people will come by and give better recommendations and tell their experiences.
I currently have 5 small angelfish in my 38 and I'm waiting for a set to pair off. Once they do I will rehome the others.