Most of the comments are based on our own familiarity and experience. What might seem easy to some, might not be so apparent to others. Many of you guys are great on Stihls, but I never mess with them, so on the rare occasion I get talked into it, I hate it. Not a problem with the saws, just not something I see enough of to get comfortable with.
Only commenting on the Huskys and Jonnys that I have many years of experience on, there are a couple chassis that extremely easy to work on. I'm defining easy as how simple it is to get in and out of them; important for a guy who might not be experienced and may have to go back in a few times during the project. Simplicity of design is the biggest factor; as in how easy is it to get where you need to without a lot of unnecessary steps taking things apart to get there. And last, being so simple and straightforward that's virtually impossible to screw it up.
254/257/262 has to be the best in that regard: Everything is so easy, open and straightforward on these saws. Nothing is in the way of anything else. Throttle links and that little choke lever are out in seconds. Easy access for changing a fuel line. Carb can be bolted on before installing a cylinder, yet is still easy to remove at any time. Doesn't get any better IMO.