Its always difficult to compare sports in terms of skill etc, but for me personally I have always felt that soccer has a higher skill level than footy (and will explain that in a bit), but having watched a lot of soccer in the UK, the thing that I realised when I arrived in Australia and started going to games was the sheer size of the ground. Now before I came here I though soccer players were fit, but it was a sort of "hold my beer" moment with the AFL players. Even if you look at time on ground, I think they play for longer and cover much greater average distances.
Now in terms of skill, one of the best ways to review overall skill level isn't looking at the best players, but at the weakest players playing at the top level. So I look at some of the guys playing AFL and their kicking ability etc, and to me its far weaker than the technical skills that you might see from defenders / goalkeepers playing at the lower end of the EPL. The skill level required to kill the ball in soccer is high (anyone who has played it knows how easy it is to attempt to control the ball to see it bounce off your foot around 2m or more away from your body, add in chest control etc.
I do tend to agree though with PT. Soccer is much easier to play at a younger age though than AFL is, particularly in a full game sim. You look at some of the auskick kids, and I love their endeavour but there are a heap of fresh air kicks etc. You don't see this in soccer, sure you see the same "follow the ball" mentality (though this is evident in almost every sport at a young age, its how you can tell who the kids are that really understand the game as they tend to skirt the packs that form). The skill level for kicking, by dropping the ball to foot, is certainly harder than most kicks in soccer (think of the skill of a volley in soccer, thats a normal kick in footy right) and I agree again with PT, that you will see a better standard with young kids at soccer, but you will also see the standard increase quicker.
I would tend to think of myself as a good soccer player, but years ago I was playing Sunday league football with a guy who had played in the 2nd or 3rd division in Scotland (not generally regarded as a great standard), but compared to most of us chumps, you could see the big increase in quality, its hard to imagine how much quicker and higher skilled it is to take the leap from that level to EPL but its a quantum shift.
I'd suspect that shift is probably more related to fitness and the really good players the higher you go up in AFL.
They are both highly skilled games but in different ways, I think there is a more varied level of skills in soccer, but in AFL mastering the kicking technique is difficult. I've never been taught to kick a footy, but I can see how easy it is to hook the kick, probably far easier than it is than in soccer, so the degree of difficulty is much higher, which is why I think I love watching Dusty so much, the degree of difficulty in his kicks is huge, but he's been so good at nailing them.