Blender, after a having a particularly frustrating time with Maya.
The reasons for my dislike of Maya were myriad, but the thing that made me finally switch to Blender was when I lost access to the modelling tools introduced in Maya 2015 after moving company and having to use an older version. In addition to the lack of good modelling tools, I had to get Maya installed on my newly built computer, after first getting my boss to remove it from an unused computer. Not only was it a hassle to get my boss to do this remotely, I couldn't even download Maya 2013 from the Autodesk website to install it, and had to download a torrent, virus check it and then use the legitimate license keys to finally get it installed, instead of the included crack - yes, the pirates provide a better user experience than Autodesk.
I'd tried Blender before, but was so turned off by the default right-click selection I didn't give it a chance, but when I did overcome my initial aversion and learn how to use (and customise) it, I discovered that Blender not only has very nice modelling tools, but good UV unwrapping tools, usable sculpting and retopo, a very nice unbiased renderer (Cycles), good animation features, python scripting and (importantly) an active, open development community and enthusiastic user base. Among the many factors that convinced me that I should keep Blender at the heart of my 3d workflow was that I know that I will never lose access to features and will never be restricted in how many installations I can have, or where I can install it.
Over the two years I have used Blender, I have gradually become more and more interested in its development, and actively follow prominent developers and users via forums, Twitter and YouTube. The Blender community is full of generous people giving their time and experience to improve Blender and share knowledge of how to use it, and although core developers are paid salaries, this all comes from donations provided by users and companies that benefit from Blender in some way. It's amazing to see that despite working on what I doubt is even 1% of the budget of a large company like Autodesk, Blender is still able to keep up with and even best its commercial competitors in many areas. Blender is frequently updated, with new versions being released two to three times a year, in addition to the developmental builds that allow users to test out new features way before a new version is released. In addition, since Blender is open source, some users even make special builds, bringing together experimental or in-development features from different sources that are not always in official builds.
Since I was recently asked by a colleague for some good learning resources for Blender, I'll share them here.
CG Masters - They do some paid courses, but there are a couple of free videos that are great for Blender beginners, such as the Thor's Hammer modelling tutorial.
CG Cookie - Whilst you can find a few free videos, most of the content is paid, but the courses are good and guide you through a topic in depth. The recently released robot character modelling tutorial looks excellent.
Blender Guru - There are a ton of free videos on how to do specific things in Blender, as well as those explaining some more general concepts, such as lighting, materials and even personal development.
Creative Shrimp - Gleb Alexandrov is well known in the Blender community not just for his cool artwork, but also his awesome tutorials. He tends to cover subjects quite concisely, but reveals many techniques and different ways of achieving results, including tricks to speed up rendering and fake things for artistic effect.
Zacharias Reinhardt - Zacharias has made some great videos on sculpting and retopo, as well as a few very helpful videos full of useful Blender tips.
Blender Stack Exchange - Probably the best place to find answers to specific Blender problems you may have, and if nobody else has asked first, you can always ask yourself.
Blender Artists - A good place to hang out to find out Blender related news and talk to other Blender fans.
Blender Cloud - A paid service run by the Blender Institute that gives users access to tutorials, textures, hdri maps, all the open movie assets and more. Some of the content is available for free, but most is subscription only. Subscription also gives you a little bit of storage space for personal projects and some other features, but I just signed up as a way to contribute to the open movies and development of Blender.
A quick tip when you are looking for Blender help via Google search is to narrow your search results down to the last year or two, as very old results, including links to the Blender 2.4 manual have a tendency to populate the top results if you don't take this extra step. Also, the most reliable way to get to the latest version of the Blender manual is to open it via the Blender Help menu or splash screen, since you will always get the version of the manual for your Blender version.
As an aside, I recently tried to pass the aforementioned Maya license to someone else as I no longer use it, but the number of license activations had been exceeded, so now the legitimately bought $3000 software is useless, instead of merely outdated. Even though the last few years of Maya updates have added a lot of great tools, I'm pretty sure I won't go back to it, as I don't really need anymore. Although we supplement Blender with more specialised programs, such as ZBrush and Substance, now everyone in the studio I work at is using, or learning Blender.