Okay, my ten cents worth; I've had both and both are very good. One could say in simple side by side comparison of what you see out the cockpit windows that uk2000 VFR's are modelled very nicely with stand out features of the VFR airfields being modelled correctly as custom objects, e.g: the control towers, airfield objects, etc - they're there in the libraries. Orbx draws all objects from its own generic library objects to represent those things - though they're pretty close - they're not exact custom made library objects for that particular airfield. Having said that ORBX DOES have many custom objects for ORBX England so don't flap - local landmarks to me down here in the southern UK have all the things that stand out from 3000 AGL - Spinnaker Tower, Fawley oil refinery, Southampton docks, etc - it's all there exactly where it is RW. VFR airfields models ONLY within the perimeter of the airfield.
uk2000 VFR's sit on whatever background you have; vanilla, FTX Global, etc - and they can sit uncomfortably with the odd elevation error and shimmering situation. Orbx England doesn't have this issue as the airfields in it are on it - so to speak.
I have found Orbx England has more up to date airfield accuracy in terms of open RWYS, taxiways and general layout, hangars, etc. VFR is showing it's age in this respect.
I can only close by stating that I no longer have Gary's excellent uk2000 VFR airfields installed but that is mainly because I've committed to ORBX England and thus there is little point in running both. Having said that there was a time when simmers were raving about using uk2000 VFR airfields with UK VFR photoreal scenery - but I didn't have that.
Sorry I can't be more polar about it. I have loved flying in both and both are very good. If you put me against a wall and held an item of soft fruit to my head I'd say; "Orbx England" but then I'd add; "Orbx England with uk2000 Extreme Gatwick, Heathrow, Stansted and Manchester."
Then, you've pretty much got it all covered and you'll have trouble keeping an eye on your instruments and not staring out the window. Hope that helps David.