i own the uchida complete mozart set, have been unbelievably happy with them for years. incredible 'replay' value, i do not tire of the recordings (it is my preferred 'quiz' music that i listen to when i take online exams/quizes for classes).
i have not felt the need to seek out any other complete set.
my advice, check different sets out from a library and listen to them, and just get the one you like best.