Some advice please: Replacing my Giant PR-2 wheels on budget of £300

I'd go for some of Chainreaction's Prime Pro wheels.  £280 and 1470g.  Can be run tubeless.  With the weight loss and run tubeless (say Schwalbe Pro Ones), the improvement in ride quality should be tangible.

Fulcrum racing 5 lg (lg is wide internal rims) £200 or fulcrum quattro lg £260 both on eBay new. 

Get some decent tyres too, conti 4000s if you don't have already. 

Your Giant wheels weigh around 1900g. Fulcrums/ Zondas around 1550/1600. I'd eat my crash helmet if these 2 wheelsets didn't perform or feel better than the Giants.

My wife had these on her Giant Avail 1 and after upgrading the brakes to 105 (which was a huge improvement), we looked at swapping to better wheels. The truth is, the PR-2s are, actually, a rather good wheelset. Stiff, light and surprisingly well built. Because of that, I think it could be all too easy for you to buy a wheelset that's no better (if not worse) on the budget you have set.

What I can tell you, however, is that my wife eventually went to a set of Fulcrum Racing 3 wheels, which cost a little more than your £300... but only a little. They are lighter and a very, very good wheelset - I used to run R3s in the winter on my summer bike in lieu of the Racing Zero Nites. The weight cost was sub-150g and breaking was good on all but the wettest of rides.

There's one other advantage to the R3s. They don't need rim tape, and while that'll save you another 30g or so per wheel, the big bonus is you're far less likely to get pinch punchers if you run the tyre pressures a little lower in order to maximise comfort. With the rim-well having no spoke holes in it, there's no likelihood of the rim tape slipping to the side and exposing a potential tube 'pinch point'. Number of punctures I and my wife have experienced in around 4K miles (combined) on Fulcrum Racing 3 wheels: ZERO!

Hunt 4 Season Aero if you can fork out another £49...

There's only one answer to the weekly "what mid-range wheelset" question.

That answer is Zondas.

Zonda's ... just note they do need a but if TLC every year with greasing the bearings and suspect if a spoke goes you really need to be good friends with your LBS as it can't be any fun using that magnet thing to get a spoke in.

However they are prety indestructable. 112 full fat kg's on them for two years and they haven't moved a mm. The guys from the LBS were in awe how true these are staying 

Vote for Campy's or Shimano over here, just search for the best discounts...

http://www.bikebargains.co.uk/components/wheels/ 

Ultegras with 30% off on there.

   Fulcrum Racing 3's for me if you can find some around the £300 mark. Only drawback is spoke replacement but mine have been perfect for the past couple of years. Hub is an easy stripdown as well. Very stiff wheelset.

You can get something handbuilt with DT R460 rims for around that mark:

https://thecycleclinic.co.uk/products/dt-swiss-r460-wheelset-road-cx-rim...

http://www.stradawheels.co.uk/product/sport-wheels/

They'll be easier to repair than zondas (no unusual spokes) and you've got the builders guarantee against failure etc

The Campag Zonda is a really nice wheelset for that sort of money, a solid performer and well built, plus they look interesting too!

This is on a rim brake bike, yes? Shimano Ultegra 6800 wheelset if you want to lose a few hundred grams?