I'm not sure I understand what you mean by value as to me it means paying a decent price for the service received. Unless, of course, you think that by paying more you get a better service, if so I hate to disappoint you but that is most certainly not the case.
To help me understand a bit, what would you class as the best value, paying £110 for an hour with a 9/10 stunner who gives excellent service or paying £150 for an hour with a 9/10 who just goes through the motions and gives a poor service. 
The £110 clearly - it I dunno, seeing a girl a second time is a bit of a strange one to me. Done it twice, once out of the area (who is an absolute stunner and on the cheaper end) and also with Jessica Jayne in the NE. Just going back the second time for me takes away from why I do it. Having a wife at home does that for me, I punt to experience typically younger girls who look in that way.
My taste from an escort is looking for that porn look girl who, ideally, offers all the CIM, OWO, DFK, etc. There really aren't many in this area that tick the box. I do think I need to revisit Morgan mind but her working just 2 days really hurts that.
It's an interesting discussion this. But if I use Cindy Veron as the example of my most recent. The pure pornstar look (because she is) and did absolutely everything I could want. She was, I think, £170 for the hour. The extra 50-60 for that hour that I would do once every other month or so would be money well spent for what I want.
What this shows is I am clearly an anomaly (on here at least). By value p, I mean my own personal value but what value the girl offers in services. Hope that makes sense.