With a life jacket. More expensive = more comfortable (almost no exceptions). Undersized life jackets are ok if you are very close in-shore (eg, no risk the weather turns quickly on you-- otherwise you would be supprised how fast waves can defeat a lifejacket) AND you wear positive buyancy clothes (eg, neoprene and well maintained dry suits-- no spray spray clothes or foul weather gear). I have both a comftable buyancy device (inshore) and an oversize inflatable (distance sailing) in my trailer box.

Harnesses are very personal. What it comfortable for one, is not for another. Full leg vs but bucket types, etc do not always correlate to comfort. For sure price and comfort are not always related. The advice above is correct. Go to a store (several stores) and hang from a rope for 10 minutes. Also bend down and make sure you can comfortably get under the boom. If you have no stores nearby, order many sizes and styles and hang a rope in your house. It typically takes 5-10 models before you find a great one-- and then you will never want to replace it ever.