i got Terra Mystica brand new and never played it once. The rules book was really intimidating. I read the whole thing and understood nothing.
Catan is awesome but far from perfect.
The one that always stayed fun for me was Puerto Rico. Loved that game.
I'm often the guy learning and explaining the rules in my group. The guys toss me the names of the games they have bought and I go to youtube to find a video like this:
Terra Mystica.
Maybe those videos don't cover everything, but you can fill holes by checking the actual rules book later. I don't think an MtG player has any right to be intimidated by a board game's complexity
I will bring up Puerto Rico with these guys, one of them probably has it.
@Cucho:
For your 7yo Catan is a safe choice imo, all the other games are for grown-ups - and some of them stupidly expensive. Catan is a totally valid game for that age, maybe even a bit much.
Also when factoring in kids, RNG can actually be a positive thing - because it spreads wins more evenly over differently capable people.
Another game that comes to my mind for the purpose of playing with a kid is
Wingspan. That's a recent game about birds - quite interesting actually, because it has many species with accurate descriptions as cards. I've played it twice and it is certainly more of a family game than an actual competitive one for adults. But since you're looking for just that, I can recommend it. Check out a few minutes of the video.