If you are trying the buy free spins feature then please go for Sticky Wilds because they give you 7 free spins instead of 15 as compared on the Raining Wilds but seriously the sticky multiplier can get crazy and you can easily hit big numbers if you get a couple of 2x and 3x with a wild maybe.
Definitely, I agree with the suggestion. I hit more crazy multiplier with the sticky wild than raining wilds so whenever I go to buy in feature games, I always look for the sticky wilds because even though it has a fewer spin, at least once a wild appears, it is guaranteed that it will stay there for the duration of the spin bonus thus enabling us to hit more paytables.