Hi, the 29 gallon would be much better, 10s can work for some fish but cichlids would be better in a 29. If you wanted to do a 10, an alternative would be some kind of Badis fish. I had some Pyjama Badis in a 10g once and they were great, I had them with rosy loches and celestial pearl danios. Badis are not a cichlid but they are a perch type fish and have a lot of personality and a lot of colour for their size.
If you go for the 29g, you could look at some of the smaller riverine african cichlids like the African Butterflies or you may be able to do a small group of Tanganekian Shell Dwellers, I dont know too much about these though but they would make an interesting tank I've always wanted to get some Nautilus shells to do a tank with these in, I've seen it done before where the tank is quite monotone with grey and white gravel/sand and white shells then their colours really pop.
Or you could look at the South American dwarfs, like Apisotgramma, Laetacara, Dicrossus or Rams. All of them do well in groups ususally one or two males to multiple females and you can build a good community around them, I always find dither fish are useful in these kind of tanks, so something like a school of tetras will give them confidence and help distract the cichlids from too much conflict.
A lot can depend on your water though, if you have soft water go for the SAs if you have hard water the Africans could be better. That said though, I have been keeping South Americans in quite hard water for a long time without issues and if you do have hard water there are things like alder cones and almond leaves that can soften your water naturally.
Hope that gives you some ideas.
Wills
