I would always recommend Alpine in the after market. Great service and great units with loads of features. The latest IVE-W535BT can also be installed to connect up to the MFSW and MFD so you can see track names, phone numbers, etc. on the MFD screen. A little bit over your budget, but what with all the features, it's a bargain.
For the top end, you cannot beat Alpine's INE-W928R VW fit radio. Specifically made for VW, it even comes with fitting kit. But you talking over a £1000 for that.
I have had issues with reception on Pioneer before and actually replaced a 2 month old unit for a customer with an Alpine because of this. Pioneer was his choice originally. He hasn't looked back since. This was on another make of car, not VW.