Which pannier racks give the best heel clearance? I've just bought a new bike (Pinnacle Neon 1 2013) which has a 42cm chainstay.
Just to be on the safe side, I was wondering which racks provide more heel clearance than average?

I'll only be using it for commuting so I don't need something as substantial as a Tubus, but at the same time I don't want it to collapse after a few weeks use.

Any suggestions?
Heel clearance is more of a pannier issue than a rack issue (as some noted in the comments). Most high quality panniers have adjustable hooks you connect to your rack, and you can usually shift the hooks to provide sufficient heel clearance. This is something you should more take into account when buying panniers. Good examples of brands that allow you to set them up to provide heel clearance are Ortlieb and Vaudé. Both are rather high-end, but they are also nearly 100% water proof.

Regarding your comment about racks collapsing: If all you carry in your panniers is whatever you use during a workday this shouldn't be an issue for the first few years of use. I have had racks break, but only after cycling thousands of kilometers on all types of hard surfaces with full camping gear.

I don't have any specific rack advice. I always just buy whatever the nearest bike shop to where I am is selling. I have good experience with Cordo, topeak and Bor Yueh rear racks and lowriders. Always the models mounted to at least the axle, I've never tried any of the seatpost mounted models.