Everyone likes different games, that is the problem. Very risky to buy a game without playing it first.
I played a LE Avengers recently, maye half a dozen games and I couldn't get into it. Difficult to judge a game though after only that many plays.
Spiderman is a great Ritchie/Lyman game. You don't see many of these for sale, which says a lot imo.
I have not played Avengers, but I have played Spiderman. Here is the dilemma - You can't play both games unless you find a collector who has one (or both). I would play both games and make a decision based on that. This is where Stern are shooting themselves in the foot. If you are in NSW - then a quick trip to AMD will solve your problem.
