Which awning to choose?

Hi everyone.  I'm new to caravanning (collecting our new van this coming weekend) and am looking to buy a full awning.  But, how do you know which one to get when there are soooo many to choose from?  I have seen an Isabella Capri and a Dorema Carrerra and the difference in price is around £600!!! What are you getting with the Isabella that is worth the extra?  If anyone has some helpful tip and/or pointers on choosing an awning, I'd love to hear from you.