Dont have the 3.6-18 personally but I have 5-25. However a friend has it plus 2 additional 5-25. His are horus reticals, mine is CCH. I also have 2 vortex razor gen 2 and an athlon chronos btr. Said friend has had most of the premium scopes and I've played with them at one point or or another. The MK5 is a very solid scope and I wont be getting rid of mine.
My opinion is all of the scopes in the MK5 price range will out perform 99.9 percent of the shooters using them. The only way to really know what's right for you is to spend time behind a bunch of scopes. Since that is not an option for most of us, pick one with the features you like (or think you will like) and be happy. People will argue all day about which is best but at the end of the day, they will all get the job done.