Another Felix

Head, more accurate 

lron Head is usually much better. The 20 base power increase on Tail isn't really worth the acc loss as it's about 20 less then most moves usually are that sacrifice the accuracy for power.

Their secondary effects are also worth considering where there's usually much more use out of flinches then a def drop.

Tail's useful if you need the coverage and lack access to other Steel Type moves or just really REALLY need whatever it's covering extremely dead right now regardless of the loss in consistency.

ln general lron Head is just much more dependable and rewards kills that require 2hkos much more than Tail.