Someone gave me a bottle of Clayton F76 and I tried it. Works fine, good details. Problem was that once the bottle was opened it went bad fairly quickly and I started to get some rather under deveoped negs from it. It had been opened by the former owner (1-2 months prior to me getting it and one batch of film processed) - once I started using it, it went bad in about 3-4 weeks.
The D76 is consistent, but again you can't really safely store it for more than 4-5 weeks or it starts changing (rougher grain, higher contrast).
The Clayton is fine if you are doing 20-30 rolls a month as is the D76. The Calyton is easier to use as it is a liquid - but more expensive in the long run.
Image quality is pretty much the same - Clayton might have a bit of an edge there though.
I mix most of my developers from scratch - easy and controllable - and I can manipulate them to meet my requirements. Yes, it is cheaper too.
Tom