As far as people say with the 'my gun is best lines' the best you can ever do is try a few out for yourself.
I have had an Angel LCD and never had a problem with it.
Had a Race Cocker from Belsales and never had a problem with it.
If you set up any gun right, be it a timmy, impy, angel, cocker, etc...you should never have problem with it.
For £300 i would recommed having a look in the classifieds and getting a gun there, there are loads of people with bargains for sale and you can play them off against each other in order to get the best price.
I would go for a gun that you would know the history of, can easily take to an approved vendor to get it fixed if there is a problem, can quickly learn how to maintain it properly and clean, and you like the look/feel of.