With a tank that size you have a huge range of options. If you ask a vast group of individuals "what should I get?" you will get the response of what we would get if we had your tank.
Since it's your tank, ask yourself some questions to get in the right direction to make you happy...
1. Would you rather have tons of little fish, or a few bigger fish?
2. Which is more important, having fish with personality or your tank looking like a piece of art in motion?
3. How much time/energy do you want to offer the tank after it's established and stocked?
4. Is there one kind of fish that you've seen/heard of that entices you more than any others?
I would suggest doing some research on the basic different kinds of fish (cichlids, dwarf cichlids, african cichlids, gouramis, live breeders, oddballs... just to name a few). Once you find a general idea of what you are interested in then research to find out what ranges are out there and see what grabs you. Chances are while doing research there will be one (or several) kinds of fish that you decide you simply must have. Learn a lil about them and make sure you still want them, then see what other fish will happily coexist with them. When you get to this more narrow end of your quest you will have much more specific questions looking for facts about fish as opposed to individuals opinions. This is the time when a forum like this is a huge asset. But asking us such a general question is opening yourself up for many different responses pulling you in many different directions.
Remember... until you stock the aquarium... it's your tank to build design and plan out to make you happy... but once you stock it... it's theirs to change, screw up and rearrange to make them happy, lol.