My vote goes for the Asus RT-N66U. I did the same research and concluded that offered me the best combinations of features I wanted plus performance. Unless you have devices that support 802.11ac I don't see any point in paying extra for the RT-AC66U.
The RT-N66U is top of the chart at smallnetbuilder.com in terms of wireless throughput and gets an excellent review for other aspects too, particularly wireless coverage. You can read their reviews of the Asus models here:
The best things about it for me are:
* excellent wifi coverage - better than any other router I've tried (eg I can stream iPlayer in rooms where I couldn't even log on to wifi with other routers)
* custom firmwares available - the Merlin firmware adds useful extra features to the standard Asus firmware (eg I use OpenVPN for remote access)
* stability - never had to reboot it so far (other than for the usual things, like firmware updates).
PSS/BT Gold > Compuserve > Dircon > Zen > Be Unlimited > PlusNet Unlimited Fibre