I'll take a stab at this briefly. Tiger barbs, danio's, cory's, tetra's, and (I think) mollie's, all prefer to be in schools/shoals. They'll all exhibit more natural behaviors, feel more secure, and look better in your tank because of it.
Tiger barb's, especially, are known to be fin nippers and will likely kill your angels given enough time whether in groups or alone. An angel's long and flowing fins will likely end up too much of a temptation. Same goes for your proposed black skirt tetra.
I've never kept blood parrot's, but a quick google search tells me they get up to 8 inches in size. Whether or not that's too big for you to want to keep in a 50 gallon tank is ultimately up to you, but a fish that size might make short work of some of your smaller fish (I'm thinking the mollies and barbs here, especially if you get them at a smaller size). Two of them, might actually be too big.
Blue gourami's can also be semi aggressive in my experience. A quick google recommends one male per tank.
I would be rethinking your tank right now. I don't know if you're just starting out, or if you've been doing this for ages, but I feel like what you have now is a recipe for disaster. Sure, they might survive, but I can tell you from experience that the cory's, tetra's, and tiger barbs look and act a heck of a lot better when in groups. Forget about the possibility some of your fish (tiger barbs, I'm looking at you!), might badger the others to death thereby flushing your hard earned money down the drain.
In your situation I would choose between the barb's or the angels. I would probably get rid of another schooling species to and increase the size of the others.
In my limited experience, I would rather have larger #'s of one fish than smaller #'s of multiple. It just looks better visually to me. Most of all, have fun!