I never build slingers anymore early on. Either it's warriors (for strength) or scouts (if scouting is an option). I will later in the build cycle build *one* slinger to trigger the archery eureka. Warriors increase your city defense by 10 when inside, slingers not at all. This alone is the difference between life and death in many a Deity rush. And, as was said above, the only variance would be scouts, who can bumble around stealing chickens and distract enemy units from a better target. Slingers at the top levels are just weak. I mean, especially when considering the deity combat bonuses -- the less I need a ranged unit right next to another unit, the better (hence, I'll build archers all day -- and by that time you have the 50% policy card to build them quicker, so no real need to upgrade 3 slingers). If I happen to trip the Archery eureka from a hut, I don't even bother building a slinger at all.