In the beginning, my first choice for anti-malware was Adaware. That is until they came out with the 2007 version. A complete overall of the interface and the program was never the same again. I ended up fixing more problems caused by Adaware than the malware itself.
I stopped using it after that and never went back. Adaware is still available from here: http://www.lavasoft.com/
When I first heard of Malwarebutes: https://www.malwarebytes.com/ I refused to download it because there was a fake scanner program going around at the same time with a similar name. Eventualy I realized it was a legitmate program and decided to give it a shot. It's now my first recommendation.
But, the latest version, v3, has me wondering if they are not following in the path of Adaware. It seems more bloated and clunky and I had to remove it from two of my computers because I couldn't get it to work properly.
I also installed it on someone else's computer and couldn't get it to run.
I currently have version 2 something on my main computer and decided to install version 3 (current as of this writing - 22.214.171.1249-10103) to see if there where any improvements.
One issue I did have before was that Malwarebytes would automatically install the premium version without giving you the option to opt out during the install as before. This time it installed the Free version.
Don't you hate it when things go right when you expect them to go wrong. :-)
Anyway, if you installed the premium version and want to switch to the Free version, just open the program, go to the Settings tab down the left hand side, then on the top tabs, click on My Account and click on the Deactivate Premium Trial button.