Hi Phil,
its horses for courses mate. IMHO it depends on what you fly and at what speed. If you flying at several hundred knots below 1500 feet the world is a blur in real life. If you flying GA type stuff at low level, and if your setup isn't up to dealing with it, the UK VFR stuff can get blurry low down, but it depends on your settings. As an example, I've just bought the upgrade from V2 to V3 of the GenX VFR. Here is the Beaufighter at the sort of altitudes your talking about over Newcastle, and I don't find it blurry.
Here is the Buccaneer at a similar altitude, but at pretty much full chat....
And here is the same Buccaneer but after I've paused the sim and its had a chance to draw the images...
The thing is, even in the blurry image, I can work out where I am easily enough. I can still use it for VFR if I choose. What the UK ORBX stuff gives you is an approximation of the area with 3D buildings, but that only loosely resemble the area. If you look at those last two images you'll see an area to the north in the blurry shot and immediately to the east of the cockpit in the paused shot. I know that this is Balliol Business Park. Yes I live in the north east, and I'm familiar with these areas, but I can look out of the cockpit and work out were I am. With ORBX, I can look out of the cockpit at lots of 3D models with trees etc which looks pretty and is an approximation of Newcastle. Yes it has most of the A roads, the river Tyne / Wear etc, but can I put the aircraft in that same position and say, that's Balliol business park, no.
It really comes down to what you want to see when your flying. I usually fly airliners or big props, so I spend a lot of my time up high (unless I'm flying the fully loaded Argosy

) I also like to know where I am, for example If I'm driving past a place and notice a disused airfield, I'll not just go and look at it on Bing maps and Wiki, I'll jump in the sim and fly over it, that's what I enjoy.
If you'd rather see 3D models that are pretty accurately positioned to represent the types of building in a particular area, but your not to bothered that its not what you'll see if you were really flying, then the ORBX stuff is a good option, particularly when you consider its more frame rate friendly for many folk and quite a bit less expensive that all of the UK GenX stuff.
So what type of thing do you like flying Phil?
p.s. I should also mention my PC specs. Not right up to date, but a good all rounder. Intel i5 2500K, 8GB RAM, NVIDIA 560Ti, SSD