Ticketmaster / GetMeIn
I wouldn't buy from Ticketmaster if I could avoid it.
I was horrified to find that they own GetMeIn - which means that Ticketmaster have no incentive whatsoever to worry about getting tickets to valid fans - they'd rather they went to people who will resell on GetMeIn - double profit!!
On the other hand, I have just opened an account with Monzo.