Try AppTrap. Pretty slick, usually gets everything.
I suggest you not leave it on all the time though. Legit updaters often move the old version to the trash...and then AppTrapp can delete everything associated with an app.....like the license or preferences.
Easy to turn it on, drag something to the trash (that you want all the parts removed/uninstalled), and then switch it off again.
I use AppCleaner. I like how it finds the files, but gives me the option to be the one to actually delete them (as I personally prefer this step not be automated). It seems to do a reasonably good job at finding most of the associated files, returning the results in a single window, and providing a decent interface to allow the User to inspect each of the files in the Finder before deleting. It is IMO a little bit faster than using the Finder to search System Files, and does a good job at picking up associated files that may not contain the Apps name in the file title (e.g., some iStat files may only say Bjango in the title.) The developer is active on this forum.