Measure it, 'long' isn't a measurement! The length makes all the difference, for example when considering active fish which like to swim along the whole tank vs slower fish which just go with the flow.
Also some input on what you like such as colours etc would be helpful. Do you like shoals? Individuals? Active fish that occupy all areas, ones that hang out at the top/bottom?
Try searching the forum for '10 gallon stocking' - there are loads of threads already where people have asked the same thing and recieved lots of different ideas.
You must have SOME idea of what YOU would like in your tank?