Which i5 are you buying, one with HD2000 / 3000 or the new ivy bridge with I think HD4000 graphics, if the latter make sure your board supports HD4000 graphics (I think all the Z77's should), this will obviously give you the best onboard graphics experience.
I also prefer asus and I would get the M Pro over the V LE. Can't see why an MATX board wouldn't be sufficient, there are plenty of nice MATX cases now which will save space and provide sufficient cooling.
For £25 less the P8Z77-M looks pretty good too:
http://www.ebuyer.com/363737-asus-p8...rboard-p8z77-m