Do you have a specific space in mind as I think 125 liters are more common and a more common foot print that makes it easier to suggest a stocking plan.
Don't be put off by the overly common reputation that Cichlids have - haphazard and generalising labeling in a lot of books and shops make people switch off to this fantastic group of fish when in reality they are incredibly intelligent and make great interactive characters in a tank - there are plenty of cichlids that will cause very few problems in a tank - and lets not forget a lot of the common centre pieces in a tank can also cause issues red tailed sharks, gouramis, mollies etc.
If you like cichlids there are plenty of options for these kind of tanks but it depends on what direction you want to take the tank.
You could go with a pair of medium sized American Cichlid and then stock around them. Something like a pair of Blue Acaras or similar Acaras with some Dwarf Hoplos or Flagtail Catfish and some kind of Disk Tetra would work nice - things like Lemon Tetras, Flame Tetras, X-Ray Tetras, Pristella Tetras etc
Other options for this kind of american tank would be things like Rainbow Cichlids, Firemouths/ Ellioti and other dither fish that would work would be things like Swordtails, Brochis Catfish, Spotted Headstanders and if you dont mind mixing continents you could look at things like Black Ruby Barbs, Oddessa Barbs etc and some of the small/mid loaches would work like Zebras.
Or you could go for a Dwarf Cichlid tank with things like Checkerboard Cichlids, Laetacara, Nannacara, Bolivian Rams or Apistogrammas. These would work with smaller fish and would allow for more fish in the tank over all. In a 3 foot tank I would look at a set up like -
A mix of 6 x Laetacara Dorsiger, Laetacara Curviceps or Nannacara Anomala - so like a pair of each or three pairs of one or two pairs of one and a pair of the other etc
10x Dawn Tetras or Glass Blood Fins - or similar torpedo shaped Tetra
10x Panda Cories or 15x Cory Hasbros
2/3x LDA 010 Red Lizard Whiptails
An other option would be to do a tank of smaller Tanganyika Cichlids from Africa which would be a tank of just the cichlids but in here you would be limited with the type of fish you keep with - I would suggest opening a thread in the old world cichlid section for more info on this though
Hope that helps
Wills