Arcadia Quest is fun and very playable right out of the box as a group game, and I really like the minis and they're all preassembled
(I like the big head/chibi style, if you don't you might disagree)
dakka thread on Arcadia Quest, read backwards as the stuff at the start will just be about the
KS & delivery but some of the stuff at the end will show you a bit of what is in it and the issues
http://www.dakkadakka.com/dakkaforum/posts/list/330/580108.page#7506955
I don't have Myth myself
but from what I've read about it the game is not so playable out of the box with a pretty confusing/poorly laid out rule book including refrences to
KS only content.
(although if you can be bothered printing out a bunch of
FAQs from the net these problems can be solved and leave you with a reasonably fun game).
dakka thread on Myth, read backwards as the stuff at the start will just be about the
KS & delivery but some of the stuff at the end will show you a bit of what is in it and the issues
http://www.dakkadakka.com/dakkaforum/posts/list/750/516351.page#7393626
of the two offered at a similar price point I'd go for Arcadia Quest