But I'm not a longtime Warhammer Fantasy player. I always was interested in Fantasy, but the model count required seemed too high and the ruleset was too complex. As a fervent Warhammer 40K player, I just didn't have the time or money to join in with my Fantasy brethren.
Age of Sigmar changed that. It kept a lot of the things that made Fantasy attractive. The models are still fantastically good, as you would expect from Games Workshop. The characters and armies remain flavorable (although the fluff did suffer a bit in the transition, however). You still have that high fantasy flair.
But Age of Sigmar is more accessible, I think. The basic ruleset makes it easy to pick up, especially for 40K players. And you can scale the game to whatever size you want. Skirmishes to epic battles are possible. I think the sweet spot is about the equivalent of a 700-1000 point game of 40K, but you can easily go higher or lower.
Yes, you do need to customize the game. It's not great "straight out of the box" with complete strangers as opponents. You need some prior consensus on what you and your opponent want the game to be. In our Kidshammer group, we play it as an introduction to table top wargaming with lots of house rules. For example, we play tournament style with a shared primary objective and individual secondary objectives worth variable points (a la "strategy and schemes" of Malifaux) with many of the objectives taken from 40K (Kill the Warlord, First Blood, Linebreaker). You do need to work out some kind of comp, but it can be quick and dirty and doesn't require the list accounting that goes into playing 40K.
If any adults (well, non-kids) want to give Age of Sigmar a try, let me know. I have a ton of figures that I can share for a demo game, and I'm happy to teach the ropes. If there is interest, I'd like to host one of Games Workshop's new campaign events at Victory Comics this year. If you are a former Warhammer Fantasy player, dust off your Fantasy models and get them back on the table where they belong. And if Age of Sigmar is not your cup of tea, there's always Mantic's Kings of War to give a try.