What size and kind of wood are you generally cutting? What saw(s) do you currently have? How often are you cutting? When you cut, how long are you cutting at a give time (ie 15 min to get a limb out of the way, all day to get firewood prepped for winter, or somewhere in the middle?
I run Stihls, and can't really comment on any of the other brands. I have an 024, 026, two 036s, 064, and an 066. My 024, 026, and both 036s wear an 18" bar and run .325 chain. My 036s are set up to run 9 pin rims and I run the depth gauges shorter than spec (.030 to .035). They outrun my 026 by a fair amount, and would come very close to keeping up with my 064 when cutting stuff in the 12" range. I normally use the 026 for limbing and cutting stuff under 8" (which isn't much), and the 036 saws do most of my felling and bucking.
I'd pass on the 362. My understanding is that it's a turd compared to the 034S/036/MS360/MS361. If you really want a Stihl in the 60cc range either find a used 036, MS360, or MS361.
Practically speaking, I wouldn't go any smaller than an Ms261. Their smaller saws are only a LITTLE lighter, but you loose a LOT of power. The 261 was a noticeable step up from the 026/MS260 (3.5 hp to 4.0 hp). I've not run one, but at a measly 10 lbs, 4.0 hp is a lot of power for such a light weight saw. Personally, I would recommend running it with an 18" bar instead of a 20". I'm sure it will pull a 20" okay, but its extra bar and chain length that the engine has to pull, and weight you have to carry around. My 026 saw does okay with an 18" bar, but would be better suited with a 16" (I mostly cut hickory). A friend of mine has multiple 026 saws that he's been using since they were new and came to the same conclusion many years ago. He runs 16" bars on all of his 026 saws. I only run the 18" to minimize the number of different bars and chains I need to keep track of. Based on the saws I have, and how I use them, I'd say the 261 with an 18" bar would be a great option if 75% of what you're cutting is under 20". If you're routinely getting into wood that's over 24" across, then I would look at something bigger. That would be either a used MS361 (or older), or a new 400 (almost the same weight as a 362, but significantly more HP) which is going to be expensive. My guess is that the sweet spot for the bar length with a 400 will be 24". Realistically, between the 261 and the 400, Stihls 360 series of saws is becoming obsolete.