Battle-forged all the way!!
Pretty sure it's been shown by arena fighters that it has the greatest increase to your damage.
This is true It does give the highest damage increase, out of the crafted tech kits anyway.

For general hunting, I use Sharper. My ancient dragon isn't a Lunus (And his TP are all messed up too at the moment >.>) so he doesn't have as high t/c or dex as he normally would - so I use sharper for the extra to-hit.

If I had 600 tp in tooth and claw and some in strength or dex, I'd go with the Battle forged because I wouldn't need the extra hit.

Deadly I've seen is mainly used by caster dragons who want to get the most out of a decent melee ability (ravage), though in my opinion Sharper V is better for casters as their melee hit chance is quite low (usually) and the gain to Ravage doesn't outweigh the damage increase Sharper/b-forged would give to every single attack.

As for rending...I personally never use this for general stuff, as my gold rage kills almost everything the first time around anyway and even if it doesn't, my target doesn't live long enough for me to want a ~80dmg/tick DoT and give up hit chance. However, it is wonderful against some epic mobs. I could also see a caster using it if they wanted to apply the DoT and then kite with AoEs.