surely not sage naruto since you can get him for free in sage treasure and he will eventually appear in one of the shops.

yes you can get sage naruto for free but that's a long road, I have been playing for about 1 year now and I only have 34 of his frags for free and almost half of them are from a mission box event, you sure you can wait that long for sage naruto because look what they did with konan and she isn't even that good. also get jounin minato instead because he is just as good and fits in more teams then sage naruto, Don't get sailor sakura if you don't have mei roshi Han etc.

For sure Jonin Minato