1077 answered your earlier question, and I certainly agree with him.
On the angels, they are best in groups of 5-6, and must be added at the same time to avoid trouble. You can read why in our profile, click on the shaded name Pterophyllum scalare. They also will go after small fish, though not barbs, but the rasbora might be a target when the angels are mature at 6 inches with 8+ inch fin spans. Severum are much the same, at 8 inches a threat to any smaller fish.
African rift lake cichlids are not compatible with other fish as "community" due to their significant difference in water parameters and behaviours. They deserve their own space.
"Large centerpiece" fish are not easy, and usually impossible, unless the tank is very large, thinking of several hundred gallons. One must remember that while certain fish species may be found in the same habitat naturally, they usually occupy very different areas and seldom come into contact. Or if they do, there is space for the smaller to escape easily, and the larger seldom bother them. In the aquarium, no matter how large in a home, it is still a relatively confined space for any fish, and they have no escape from other fish.