What size tank do you have?
Bluegill and shellcrackers are OK, but they get big and can be very aggressive. I wouldn't keep these unless you have 100 gallons or more. You can keep one or two in a smaller tank, but what fun is that?
There are a lot of nice, somewhat smaller sunnies, like longears, orangespots, dollars, redspots, shadow bass, etc. Most of these are prettier than the big guys, and somewhat less aggressive. These are great for 40 gallon plus tanks.
There are also some very small sunfish, such as bluespotted, blackbanded, and banded sunfish- these should not be kept with bigger sunnies, but are a great choice for a smallish tank- 20 plus.
Also be sure to check out your local streams for great community fish. Take a dip net and sweep through vegetation or use it as a kicknet (plant the net flush against the substrate and shuffle your feet through the gravel upstream). This will produce darters, dace, shiners, topminnows, madtoms, and other cool community fish. You can even keep these little guys with the smaller sunfish.
