Saturdays?
Seriously, you're going to have to try some of these out before committing, I wouldn't dream of recommending a seat without it being tested first. Granted, I took a punt on the Sparco Sprint V but at the price I was paying for it and the usage of it in a track slag, I could take a gamble. If you're spending a good few hundred on something quality for the Zed, I'd definitely try before you buy
Might be worth popping to a local trackday near you if you get a chance and see what people are running there, bound to be at least a couple of different options.