I have a Asus RT-N56U router, it can do better speeds than the HH4 and has more controllability (ie MAC address filter)
The setup and configuration should be easy (though some have had dificulties)
Wireless wise it's capable of 450Mbps, unlike the HH4 (300Mbps)
The Netgear N900 WNDR4500 works as a good replacement for the Homehub also. We recently replaced ours and everything is working much better.
The Draytek all-in-one is a reasonable choice if you want everything all in one box, but it is an unsupported configuration, if you ever run in to problems you will need to reconnect your openreach modem in order to receive support.
yes does the WNDR4500 work with BT Infinity Option 2 / BT Vision ? multicasting etc ??