Personally I sit, but I have a back & shoulders problem.
From posts on this site, and others, it really does seem to be a matter of personal preference, and a preference you can only work out for yourself after several long-ish cutting sessions.
My advice would be rig up something firm enough to reliably saw on at, say, your preferred sitting height, then try it for a while. Then try the same set up but raised to your standing height for a while. Only then go for the final height solution which is good for you personally.
BTW, if you do go for sitting I strongly recommend a swivel chair without arms which is height and back rest angle adjustable. It may be just me and my bl--dy back, but I find it necessary to change the height of the seat (and the back rest angle) slightly now and then - maybe several times during a lengthy cutting session.
(Same with sitting at the PC too, but that's another story)!
HTH
AES