Is there a character that you frequently enjoy to playing as in the Mario Party/Kart games? Is there any particular reason why? And if they're not available for some reason (somebody else chose them first, they're not in the game at all, etc.) who is your second pick? Me, I really like to play as Waluigi. I don't even know why I like him, I just do. But as he's not in all the games, whenever he's not I like to be Luigi (who is absolutely adorable). I just consider myself lucky that between me, my siblings, and even my cousins, we don't really have the same character preferences. They all like to be Toad, Toadette, Rosalina, and Daisy. At least there's no fighting over characters.
I prefer Lord Waluigi too (I assume that he is in every new Mario Party game). In Mario Kart I prefer Dry Bone, If he isn't in the game then Koopa. If both aren't in the game, I take Yoshi.
Luigi is the best character because he has the most character. I like playing as him because he has so much going for him. He has pretty much always been my favorite.
My favorite is Dry Bones. I don't really know why I like to play as him, but I almost always go straight for the skeleturtle whenever he's available.