I'm 6'1 and pretty thin, so not *too* far off from you build-wise. I have a Humanscale Freedom chair. Paid a good amount of money for it, but I've had it for more than five years and I work from home as a software developer, so that's a lot of hours with ass in chair. It's held up pretty well and is pretty comfortable. I've used Aeron and Steelcase in offices before. Hated Aerons (if you have long legs, it digs into the back of your thighs) but Steelcase are nice. I really hate all the "gamer" type chairs as well.
As far as ergonomics, there really isn't one "right" way to sit in a chair (though there are certainly "wrong" postures). What's more important is that you can change your position at least a bit every fifteen minutes or so. No matter what position you are in, if you hold it for hours at a time, it's going to mess you up. So when you're trying chairs, prioritize ones that let you move around a bit and be comfortable in a range of different positions.
As far as ergonomics, there really isn't one "right" way to sit in a chair (though there are certainly "wrong" postures). What's more important is that you can change your position at least a bit every fifteen minutes or so. No matter what position you are in, if you hold it for hours at a time, it's going to mess you up. So when you're trying chairs, prioritize ones that let you move around a bit and be comfortable in a range of different positions.