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With a tank that size I would go for something that gets bigger, such as Pelvicachromis humilis, Benitochromis (sp?), or Steatocranus. You should also be able to get a pair of Pel. pulcher, taeniatus, subocellatus or roloffi in there. Some af the larger Nanochromis (parilus, transvestitus) would be good too. Plant it heavily and add dithers. UD catfish make great west african dithers, as do any of the various congo tetras.
Ted makes some good suggestions. I think it is a matter of personal preference. With athat sized tank, you easily could house any West African. It is just a matter of how many and their tankmates. I think that i would go for 2 species of relative similar size and aggression levels and find some active dithers to put in there. Anomalochromis with with a Pelvicachromis sp. might be nice or Nanochromis with Pelvs. I have found Teaniatus or humilus species to do well with some Chromidotilapias.
I say find some fish that you really like and then check back to see if people have some suggestions for you about them.
Good luck,
Neil