I own far too many saws to follow the rules in these "one saw" threads, but I guess I could mention favorites by size and what has seen the most use over the last couple of years.
40cc class-242XP. Most saw classes have several saws that vie for the top spot. IMO the there's nothing even close to the 242 in it's class. Mine has a gasket delete and muff mod and is awful close to most 50cc saws.
50cc class- 2150 with a 2453 jug on it. .325 8 pin. The only saw I own that always has fuel in it. Reliable and very quick. No problem handling wood up to it's 16" bar length.
60cc class-Tough call here. 562 is just about a perfect saw. But a 262 and a 257 with a 262 top end also get used a lot.
70cc class- Any one of several 372/2171 chassis saws that I have. Pretty much ideal all around saws. Including one 365 I ported that out cuts stock 72's.
90cc class- Jonny 930Super is my favorite here. With the second generation cylinder that has cut outs to the case it has a little more grunt than 288's and such.
And to keep the post going by finding more...........(this is the same thought process by which we justify CAD acquisitions)
"Winter use": 2163WH cause the heated handles are nice on a cold day.
"Huge wood": Just did a 30+ inch ash with a 2100CD, so ya gotta have one of those too.
"Leave out in the workshop to grab it when I need it saw": VERY ugly 52E that I patched together from the junk pile.
"Old Swede"- Jonsered 70E. The granddaddy of the 70cc class. Was ahead of it's time and still fun to run.
"Old Mac"- ProMac 60. I love this saw. Nice power and really light for it's time. Great handler too.
"Old Homelite"- SXL925. Great saw, gobs of torque. If it had mounts, everyone would yank them out.
I'll try and think of a couple more......................
