Much as Pen, paper and codex is my preferred method, and served me well for many years, it just can't be trusted around many of the younger players in my area. I still use it, but when I want it to be read by everyone, I'll plug the numbers and options into AB for printing.
Literacy, numeracy and handwriting skills are just not what they used to be, I'm afraid. Most schoolkids these days use a computer word pro to submit work to teachers, and run it through a spellchecker first, too. They don't need to learn this stuff, the computer does it for them.
At my club's tourneys, we insist on either an Army Builder roster file (.rst) or a word or excel file for submitted lists (as they need to be read by all of your opponents, as well as the orgs).
The older players use the excel or word files (.doc/.rtf or even .txt are acceptable) as they are ALL more legible than most of their handwriting, even if they have perfectly legible handwriting.
I use AB because I bought a copy when I was validating lists for the tourney, and most players had it. It's handy, but I also had a copy of all of the codices with me as well.
Before that, I used Excel, which with its autosum function, helps to keep track of points as well.