It would be interesting to see how he'd do in a more competitive league.
La Liga is almost Scotlandtastic in the way the top 2 are above everyone else.
There's a 25 point gap between first an 3rd which is the same as the gap between 3rd and bottom. Real Madrid's goal difference is +65 , Barca's is +60. Valencia in 3rd are the next best at +11. The gap in quality is pretty stark.
That said Messi has done it at CL level year after year so that's not too big a stick to beat him with. But he is also playing in just about the best club side of all time. I thought our Invincibles were pretty special, and they were, but they weren't as good as this lot.

It is hard to compare players because of the different teams/eras they play in.