Seriously? The op's struggling to give any meaningful or relevant information about the issue with consumer kit that's dumbed down and you want to spec him a SOHO/Business class router that's well known for it's less than user friendly config that used to require you to drop to command line to config it?
Op, based on your earlier posts and ability to describe problems then please, please don't buy an edge router, it's a device that has an expectation of basic networking knowledge that from your description of the issue you have it appears you just don't have. I'm not trying to be rude here, what you've got as it's a more than capable router so I suspect the issue is going to be something else. 'Slow to respond' with no context could be the device you're accessing on For example if you're hitting a local server then spinning up an HD will take time, the remote site you're accessing could be slow, someone else on the LAN is hammering your uplink to oblivion or hundreds of other things that aren't anything to do with your router.
So if you could elaborate on 'slow to respond' and possibly give us a clue about what you're actually doing and what else is going on then we could save you a few hundred quid. If not then don't be surprised if you have the same issues and have paid a few hundred quid for the privilege.