If you're after a 600, think about what you'll do with it. Are you commuting, pleasure riding, or do you want a bike that won't give you problems?
If you want to commute, then I would go for either a Suzuki Bandit, A Suzuki GSX650F or perhaps even a Yamaha FJ Fazer.
If you're more into taking the roads as they come, then I would say either the Yamaha YZF-R6, Honda CBR600RR or the Suzuki GSXR600. They're the base set of sportsbikes.
Something else which is actually a rather underrated bike is the Kawazaki ER-6 F. Same engine as the Ninja ZX-6, just has slightly lower power output for better fuel economy.
As for reliabilty, Honda would almost certainly be the way to go. A CBR600F could easily get 70k on the clock without too much trouble (New clutch and uprated sprockets would be the limit, I'd imagine)
Price wise, most competitors price their bikes within the same range. Value for money would lean towards the GSX650F at only £5k. Has the same engine (with downgraded power) as the GSXR600 and looks very similar to the GSXR.
Another thing to worry about is Insurance. The GSX650F will be the cheapest of the lot, and either the CBR or the R6 will be the most expensive.