Annoyingly I wrote out a long complicated reply a couple of hours ago and managed to lose it through some cyberspace glitch, so here's the short version -
MT500s or their other manufacturer equivalents wouldn't be a bad choice - here's my 10 yrs old version -
You can pick these up cheap as they're not very popular. Picking something that's not very popular is going to be the only way you'll get something reliable for your budget - and even then you're probably going to need to know your way round a set of spanners. The only downside is that if you already ride a F650 they won't be different enough.
From your list I'd forget the VFR (for £2k it'd be like russian roulette), the C90 ( too slow), the V50 (I owned two - just forget it!) and the Enfield (see VFR reason) A Pan Euro could work as could any of its siblings - K100, a number of Triumphs etc. They'll all be starship mileage for £2k but that's no bad thing if you're going to buy and sell after a month or two. For me these ubercruisers are only one step / two wheels removed from a Renault Clio though. Nothing wrong with them but just big, heavy and more work than pleasure.
My alternative choices at the moment are these -
A 70's 400/4 Honda. You can still pick up a good one under £2k
An old Kawasaki 500 two stroke. These days though classic mania has driven prices way over £2k. At 20mpg I can't understand why.