There are 53 distinct types of nuts on the planet. I don't think you will manage to sub-categorize elders into 53 distinct types, but there are all kinds of elders.
Typically, elders are selected by their ability to promote and demonstrate full faith in the corporation of Watchtower. Accepting and using their doctrine on the platform and being willing to do any menial task they ask of you helps.
But it isn't that simple. Some are made elders because their family donates money. Some because they pioneered long enough to impress the other elders, or because they married into the right influential family. While I was made elder for the first reason I list, demonstrating and promoting the corporation, I was made an elder kind of fast because I studied with the elder who wanted to be a huge fish in a small pond, and nothing was more impressive than all his male students making elder quickly.
Being raised a JW, you get there faster if your family already has "men in position" and especially if they hid any of your youthful indiscretions to protect their own positions. If you were converted as an adult, you won't have your youthful indiscretions held against you. So many different paths to elder. Hell, someone who buys a minivan for recruiting every Saturday and gives the C.O. a green handshake every 6 months could get there fast.