Sum-to-10 is my favorite way to build, because it gives you a great deal of flexibility over Priority, while being a lot faster than Point Buy.
If you're interested in an analysis of "what method results in the most powerful characters", read my post on the Shadowrun subreddit
https://www.reddit.com/r/Shadowrun/comments/uyl3aq/6e_point_buy_and_life_path_in_companion/Point Buy results in the most powerful Mundane characters, because money is undervalued.
Priority/Sum-to-10 give you the most powerful Adepts, because D priority Magic is crazy powerful.
Life Path, if you "cheat" and guide it where you want, makes the most powerful magicians because your spells are free, and special attributes are weighted the same as regular attributes. Mystic adepts created this way are incredibly better than other methods, so much so it's fair to say it's broken for that archetype. This is because mysads get 1 power point for every point of magic, just like adepts, instead of having to split.
