Welcome to the Planted Tank and congratulations on setting yourself up with a hobby that is sure to repay you back with beauty and awe given that you put in the necessary time and maintenance for it!
I currently maintain a planted tank with mainly african cichlids as well as a Black Convict like yourself, parrot chichlid, chinese algae eaters, senegal bichir, plecos and a Blue Freshwater lobster.
In regards to what a good fillter would be, it really depends on what you plan on putting in your tank and what you expect from it. I, myself, like to have more filtration than necessary and usually account for much more filtering than simply the "size" of my tank. I think these would be worth looking into
-EHEIM 2211 external canister filter
-FLUVAL 206 external canister filter
Different factors will affect or aid your filtration as well though
-How stocked you want to have your tank
-Plants? No Plants?
-If yes on plants, what type of fertilizers would you be using?
Keep in mind that a great filter will do wonders to a tank and help you out tremendously but you should still do maintenance and not rely on your filter 100% to do the cleaning for you. Also, when you look into buying filters, if you ever plan on having filter media within the filters, that would affect your filter flow of GPH
(gallons filtrated/ hour). All filters that state their GPH on the specificaitions will almost always make you aware that this is WITHOUTH MEDIA
I currently have a 55 gallon long tank and just orderd 2 - EHEIM 2213 external canisters (up to 60 gal). Theoritically speaking, one would suffice, but i wouldl like even better filtration and on top of that, nice water flow.
Good luck on your filter search and remember that everyone will have different opinions about what is "better". You have to just get in there and start working with it and test out what you like and get an idea of what you are looking for.