Gems.

[Allybug01]

Well what should i do with gems? Gem Ck to 5, Minions to 4, Hogs to 2, wall breakers five, valks to 2 or gold for walls? O r something else

[General7100]

Minions! hehe

[Piazzw]

Boost barracks/heroes/spell factory and farm like hell

[shivampaw]

Get all your builders!
Boost barracks and spells if needed. If you do you will end up being able to do two of those things in a day...

[Allybug01]

I will gem my drags to 3 because that's only 500gems then I'll get another 500 to boost and farm then 500more to own in my upcoming push

[Benny101]

I think it's a waste of gems to use them for resources. Just gem your barracks and spell factory and raid your butt off. You can upgrade everything from your list in record time. If you don't have 5 builders yet, get those. They're the only thing you can only get with gems. It's also the best investment you can make.

[Kirky]

I wouldn't gem any of them. But on the basis you want to gem one of them I would say either mins or breakers.

Mins and breakers are both useful farming troops in certain combinations, so you would get a buff to your farming from doing either of them. The decision would depend upon which you use most.

For me, you wouldn't notice too much of a difference in one lvl of BK, and lvl 2 hogs are not strong enough to be useful. You'll have harder farming/more gemming to get Hogs to a lvl of being useful. Even then, it's difficult to use hogs in a cost effective manner due to the large DE cost.