In terms of just 'playing the game' then yeah the Jugunds are probably the most cost effective in that regard, BUT! it's hard for me to truly have an army constituting of so many kids (relatively speaking). I could only use them as auxilaries or last ditch defense not as the foundation to my empire.

but for me the Jewish Spearmen and Persian Archer/Spearmen are the best. Jewish Spearmen can be recruited by any army with a low level regional barracks, and they truly do make great account of themselves as warriors. 1v1 they aren't as effective as many of the Hellenes in the area, but the Jewish spearmen come in units of 200 rather than 120 or 160 so their numbers make up.

Same goes for the Persian Archer/Spearmen. They have great range, 25 arrows, and are good enough warriors that they greatly help the Jewish spearmen by flanking after their arrows have greatly thinned out the ranks.