For me size for wingfoil = size for windfoil, but the foils wingsize is double or even more than double for wingfoiling than for windfoil. So getting going with a 5.0 wing + 2200sqcm foil and 90L board in a 12 knot gust, or 4.9 + 900sqcm foil and 105L board in a 12 knot gust. I'm 89Kg now. I think less wind should be possible for wingfoiling with the big foil (or smaller/faster foil in the same wind, want to try our new thin and "high" aspect 1780sqcm soon!), but it remains less efficient than a windfoil sail to pump. One of my F-One teammates rides the 4.2m wing with the 900sqcm foil in 10knots, but he's magic and only 75Kg. (Titouan Galea if you want to look him up:
www.instagram.com/p/B3cYs1hokOp/?igshid=1ehiba1c42jtf)
I ride all F-One gear, except windsurfing sails, those are S2Maui Dragons.
Wing choice matters aswell. The Naish, slingshot and Ozone for example have quite flat profiles, the Duotone is quite heavy due to the boom design but I think it can be set ver full to increase power. The F-One has a very deep profile with a lot of power, but is a little less stiff in the tips than for example the slingshot (more twist).
My experience after having tried the slingwing, Ozone Wazp and F-One Swing, you can ride the F-One Swing about 1m smaller than the other two. I've only seen the naish in the shop and lifted the Duotone at the waterside.