
There are quite a few 'experts' around who can explain well, but I would say in a very general sense the bigger the surface of a foil the more lift it will have (ie it will lift in lighter wind or it will lift a heavier rider)
but the surface is one factor among others, like you mention aspect, then shape, design, thickness
- foils seem to fall into categories
- they have a lot of lift
- they turn easy
- they have speed
- they have glide
- they pump easy and keep the board up for long distances
most foils try to hit one area and then add as much of the other factors as they can
for example the gofoil maliko 280 vs the 200 will lift a heaver rider in the same wind or will lift a light rider in even lighter wind
the lower the aspect ratio the foil appears to offer better initial lift and lower speed vs lower initial lift and higher speed the higher the ratio, most low aspect ratio foils are 'fat' and the high aspect ratio are very 'slim'
- if you watch some gofoil videos where the specific foil is mentioned then check the gofoil foil info page you can see what the foil is doing in the video with reference to the specific foil design. As they function much like airplane wings they tend to do the same as the various airplane types that we maybe more familiar with.
For another example the gofoil NL210 will lift earlier in light wind and fly slower than the NL190 which has less surface area
however some riders will get a RS1150 with less surface area and a higher aspect ratio flying because they have skill to maximise the reduced drag and get all the performance out of the wing
anyway I'm sure someone can explain better than me