How many wild cards there are affect what hands are harder to get. I played for years in a game where house rules were straight flushes were higher than 5 of a kind. I got outvoted on that, but it was a fun group. They limited wild cards to no more than 3 except for one exception -- Dr Pepper (10s, 2s, and 4s) and one-eyed Jacks (hearts and spades in most decks) wild. Most hands had wild cards. I won most of the money won in that game. I personally rarely played wild cards when I dealt (2 or 3 times a night). I thought the wild cards helped me a lot because most players don't really know how to play with wild cards.
Most groups I've played in, if they allow wild cards, play 5 of a kind as the top hand.
Someone mentioned fewer wild cards in a tied hand wins. I never played that way -- the winners just split the pot. But that would add a whole new element to play.