"best" depends on number of workers, items you want to craft etc., but http://shop-heroes.wikia.com/wiki/Worker_Teams
might be of some use.
(of note: "tinkering" is only used in the bows, projectiles and guns lines, while other skills are used in many more lines)
as of 2016-09-11: Player level: 44, City: Eolythes, Blueprints: 517, Mastered: 419, Crafted: 78.61K
(except for tier 1 and some tier 2 artifacts mostly running my shop/gearing self sufficient)