Has it got to be diesel?
How about something like a VXR Vectra,or even more subtle a GSI vectra. the GSI has 200hp and a 3,2 v6.
Id avoid the Golf too. I had a mk5 GTI for 6 weeks,and it was a good car,did everything well,but i wasnt sad to see it go. It was just a good all rounder.
Im sure you could pick up a 530i or 530d for that sort of money,if thats the size you want,or a 330i/330d if you want something abit smaller,similar sketch with the C and E class,though they tend to be Auto's more than manuals. Youve also got the A4+A5 Audis,they are very good. Just depends what you fancy.
Try driving a range of cars,and see what sort of car suits you best.