It's a bit weird to me that AoE 2 is the most popular of that series, considering how much more streamlined and balanced Age of Mythology is.

For example, getting to the 3rd age in AoE 2 ASAP is basically mandatory, but in AoM you can potentially start attacking from the 2nd age. On top of that, getting to the 3rd age in AoE 2 takes much longer than AoM. So there's basically a whole lot of wasted time at the start of an AoE 2 match.