It depends on if you want to clean out tanks or pens.
I do not like tanks so I have all land turtles & tortoises.
The size is an issue also.
Turtles and tortoises are a life time commitment, so make sure when you chose. They can live 30 – 100 years.
Box turtles, greek tortoises, russian tortoises (+more) stay small, then you have red foot tortoises, a bit large is the leopard tortoises getting up to 40 pounds then the sulcata up over 100 pounds.

You can go on line and learn about each species to figure out which you want.
Some sites to read on tortoises

if by turtle you mean land turtle, not much. one will grow much larger. the larger the pet the larger the spending. a turtle can do good in a 40 gallon reptile tank. make sure if you do use a tank to get a reptile tank they are much lower, wider and longer. a Sulcata Turtois is the easyer one or leoperd toitous. as for turtles a box turtle is easy. water turtles take a lot of work. a land one only needs a basking light. of course a pin or tank and food. water ones will need a filter,pond, basking bulb and different docks. good luck