SACCOs usually operate in a particular area or among a particular group of people. Ask around if there is a SACCO operating in your area and then talk to them about what they offer. If there isn't a SACCO in your area, you might consider starting one.
If a traditional bank appeals to you more, investigate which banks have branches in your area. You should be looking for a bank that has a branch you can get to easily, and has reasonable bank charges and good interest on savings. You might also want a bank that has a lot of ATMs so you know you can get cash wherever you are.