Top of the list was a decent drysuit, things that had come to light as being important were a front entry zip, a relief zip, neoprene neck seal and high visibility. Much head scratching later I purchased the Kokatat Super Nova drysuit from the US. A year down the line and it's been everything that I'd hoped for.
Full review here:
There was one more vitally important item and that was the PFD. I saw one that tickled my fancy in the US and seemed to be well recommended., it being the Stohlquist Fisherman PFD. It's turned out to be extremely comfy to wear in the yak and has excellent buoyancy.. no complaints whatsoever.
One last important item..... a wool hat!!