Hi KingdomAlion and welcome to the forum. Don't let this search get you down. There is no easy answer to this one... I and many others here have been looking for this for a long time. To be honest the best maps I have seen are hand drawn then scanned into the computer or drawn with a drawing tablet. You might never get the look and feel of a map that took 16+ hours to draw in 2 hours using plug-ins and other people's brushes. If you could the guys with "mad drawing skills" would be out of a job. One sure fire way to have mountains that are less repetitive is to have more mountain brushes to pick from... but it is almost impossible to find an extensive set that looks the way I want. The only two ways that have worked for me are.
1.) Making my own brushes. I normally draw big and size down to make the brush. This keeps the style the same and if you make enough of them you will get a nice selection.
2.) Hand draw mountains on paper then scan, re-size, color and clean them up in Photoshop. I find that drawing elements by hand and just re-sizing them in the computer hides most of my less than ideal drawing skills.
Sorry this is not much help but this is a tough issue. On the other hand keep up the search... nothing is imposable so if you find a quick and easy way to get nice looking mountains please let us know :-)
My other 2 cents - Practice and hard work is a tried and true way to get what you want (in all of life). Never give up and you will be proud of the maps you make.