I have the Asus Maximus VII Hero z97 and I've been very happy with the board. Plenty of room, good build quality, PWM fan control - was a big seller for me.
If you think you might go water and want to cool the board, then go the Formula. The Formula will also give you the armour for rigidity and the option of painting it to match other gear
Back when I got my Hero, I wanted the Formula but the AU$ on launch was insane. Asus make a good mobo so you can't really go wrong, they'll both allow you to OC hard and have very high frequency RAM frequency support to last you a few progressions.
The only other notable thing I've heard (but not confirmed) is that the chipset housing manufacturing quality on the Formula is better than the Hero - some people reported very high temps on the Hero's but I have not had that issue on mine.
Hope this helps in some way