Use purple or blue smite. Red got nerfed, it's now only usefull in 1v1 situations for champions like Yi, WW, Trynda or Udyr... Grey smite can be usefull for a splitpusher but the purple and blue ones are sooo much better in any other situations.
I use purple when i feel i have enough CC to gank any lane and i want to farm / sustain faster in order to put more pressure on the map. Purple is mandatory on Eve and any other jungler that struggle in the new jungle.
I use Blue when i need a little bonus CC on my ganks or to prevent missing my hard CC (i use it on elise for exemple when i have to gank really mobile champions). Keep in mind that it will be harder to clean your jungle without taking damages if you're running blue smite.
In short : Purple gives you more map pressure as long as you're not wasting time in your jungle by getting bad timers / routes. Blue helps to gank cc-lacking lanes, and makes your ganks easily succesfull overall.
Edit about enhancements :
Use the Red one (armor pen) on J4 and Lee sin (and any other early AD jungler).
Use the Purple one (devourer, aka feral flare) for lategame AA hardcarries like Nocturne, Udyr, Yi, Shyva, Trundle, etc...
Use the Blue one (AP) for AP junglers that have decent ap scalling like Fiddle, Diana, and sometimes Elise or Amumu.
Use the Green one (health) for any tanky jungler but always take Red over it if you have early damages. Take it on Evelyn if you're not playing her AP (ap eve is bad actually).
I use purple when i feel i have enough CC to gank any lane and i want to farm / sustain faster in order to put more pressure on the map. Purple is mandatory on Eve and any other jungler that struggle in the new jungle.
I use Blue when i need a little bonus CC on my ganks or to prevent missing my hard CC (i use it on elise for exemple when i have to gank really mobile champions). Keep in mind that it will be harder to clean your jungle without taking damages if you're running blue smite.
In short : Purple gives you more map pressure as long as you're not wasting time in your jungle by getting bad timers / routes. Blue helps to gank cc-lacking lanes, and makes your ganks easily succesfull overall.
Edit about enhancements :
Use the Red one (armor pen) on J4 and Lee sin (and any other early AD jungler).
Use the Purple one (devourer, aka feral flare) for lategame AA hardcarries like Nocturne, Udyr, Yi, Shyva, Trundle, etc...
Use the Blue one (AP) for AP junglers that have decent ap scalling like Fiddle, Diana, and sometimes Elise or Amumu.
Use the Green one (health) for any tanky jungler but always take Red over it if you have early damages. Take it on Evelyn if you're not playing her AP (ap eve is bad actually).
APCs and ADCs are just our poor lil things we have to protect in order to let them afk-dps.
!
