I tend to push the limits on what fish to stock as I can almost always find good places/methods to move fish along if there is a major mistake and one fish doesn't fit. So that leaves me trying things and finding they work even though many will tell me it does not.
So part of the question has to be how you are set, both mentally and situation. Can you adapt and change the tank if something needs it or do you want a setup that never needs a change? If the mental part is no problem, I find larger fish are most often more desirable then younger if I need to swap out fish. Doesn't apply to some like Dempsey and large plecos but I just don't go there in my tanks. Can you easily swap a fish to somebody or a local shop?
If that is true, I highly recommend the rainbow cichlid as one which will work well with most small fish. I would not hesitate for a minute as they are one of my true favorite fish. From a cichlid standpoint, they are more often bullied than aggressive.
I have kept and bred them in tanks with guppies and Endlers but it was 75 gallon. The biggest problem I see with rainbow cichlids is choosing timid enough fish to not bully them! But when raising from fry, together with other fish, the whole group may grow up to be very compatible, even when all the reports say it will not work. I find fish very adaptable if given the right conditions when growing.
I currently have a pair of rainbow cichlids in a 75 with the unlikely roommates being two male and 4 female Protomelas (insignus) . It should not work and I'm told it can't work as the water needed is totally different and African cichlids are way too mean. But they grew up together in a tank full of lots of plants and cover and they never learned different!
If you can handle a little drama and are willing to change, go for it and it may be one of the best tanks ever!