i wana put some sort of south american cichlid, i can use this as a growout, but need to have the fish in the 29 gallon for a few months and later i can transfer them to a 60
For a 30 and to a 60, maybe a bristlenose or one of the fancy ones that get 6" or so. Commons grow atleast an inch a month, and would fill that tank with strings of crap in no time
you will get bored with convicts and firemouth after few weeks keeping them. Salvini is a good choice, but do not recommend plecos, they will clean up the eggs your fish lay in the tank, and they also produce wastes. Why not get another cichlid like pink convict or even an escondido, it should be fine if you don't add more fish.
Since you're planning to upgrade to a 60 or bigger soon, go for a Salvini or GT as some have already indicated. Both are amazing looking fish and will do great for the time being.