To get back to your original question, large cichlids do produce a lot of waste, including a group of Geophagus. You may not see as much of it because their constant sifting will break it into smaller pieces and also cover it in sand. They don't eat it, so it's definitely still there. This is why it's important to clean your filters and do frequent (weekly) water changes. Most Geos are sensitive to poor water quality, so don't assume that seeing less waste means there actually is less waste. It's still in there somewhere, either buried in sand or broken into tiny pieces and picked up by the filter.
A lot of the fish listed above (Uaru, Hypselecara, Mesonauta) are large-growing fish and will come with a relatively high bioload. They will all require clean water with low nitrates and DOCs, so if you go for these species, please know that your water changes will need to be frequent. You mentioned you didn't like your pleco because it put off a lot of waste, so you should be prepared for these fish to do the same.