Well, if you are confident in the mooring setup then go for the mooring. You will need a place to park & legally launch your tender from also. But if money is not the issue I'd prefer the slip. Water, electricity, security & ease of getting to her.
Besides, marina life can be fun ;D because there are always characters around.
Plus you get to know other boaters & learn from them.
edit: I say this as I'm on a mooring ball waiting to get into a marina, lol