Keep whichever species you like the looks of! If that wasn't already your premise, you'd want redears, since they're cheap and easy in addition to pretty.
Any turtle species will have at least one "pitfall characteristic" as a captive. Learn about those characteristics and think about how you can adjust for that. Question the reasoning behind general statements made in caresheets, like WHY do map turtles need clear, filtered water? WHY are map turtles prone to shell rot? Don't be completely reliant on someone else's experiences. Nomatter how well-read in captive husbandry (aka petkeeping recipes) for a species you are, you'll still be experimenting when you keep that species yourself!
As one short note that you're probably already aware of, get a captive-bred specimen(s) of whichever species you go with - you have to adjust far less for them than for wild-caught animals.
