Well, of course everyone thinks "Mimitchi" is one of the best characters you can get on the Connections.
Although, In my opinion, it really depends on your personal preference. Focus more on, how you raise your Tamagotchi, how many training points, and most of all how much fun you can have with it.. Dont worry too much on what characters you get, to this day no one has got a guide on how to get a specific type of character on a Connection (or for any other version for that matter I think, besides Oyajitchi)
So, what it comes down to is your personal preference.
//haze