Something that hasn't really been addressed here is if this is a one saw plan, meaning you plan to own just one saw for all your needs? If so, I personally don't think a 50cc is a good one saw plan, I would jump to a a 60cc saw at a minimum.
I am not a fan of any one particular brand of saw. I supply a lot of wood to people and restaurants so I cut a massive amount of wood and use a variety of chainsaws and have for years. So I have a good bit of experience running many different brands. In my younger days I kinda fell on the Stihl bandwagon but as I got to using different saws, I discovered it's a whole lot like the Ford/Chevy/Dodge argument and you have your faithful followers with no real experience of the other brands. I own and use Husqvarna, Stihl, Echo, Dolmar, Makita, and Jonsered saws and like them all.
There are only a couple of Stihl saws of the current offerings that I would buy today and the 261CM is one of them. I actually do own one along with an 026 and both are great...
If I wanted a current production 50cc saw, there are 3 that I would buy. Echo 4910, Stihl 261, and the Husqvarna 550. Probably in that order. I own all 3 of these. The 4910 is about $300-350 less than the other two and will cut right with them.
If I were buying a 60CC saw, it would hands down be a Husqvarna 562XP MK II. I love mine and use it pretty much daily. I don't think there is a better 60cc out there than this one.
I have heard much love for the Stihl 400cm but have never operated one. The power to weight ratio is something to behold though. And from what I understand, they will be changing them soon so better get one while you can.
Anything past the 261, I tend to lean towards Husqvarna as I just don't care for Stihl's line past that mark. I think Husqvarna owns that territory. In my parts of the world, every arborist company you see is running Husqvarna. These are guys who depend on their saws to earn a living.