my lats are my favorite spot, although difficult at times if I'm sore. It helps to have some beef there to inject into. I can clearly see my veins which is also helpful.
Biceps are on par with calves. I would not recommend. I literally could not sleep the second night after injecting. I put my arm in a sling cause that was the only semi comfortable position. Fuck that.
traps are ok. I once hit a nerve and jerked and the needle got caught inbetween my head and my trap in a sudden jerking movement. Needle got buried and bent. I have been to gunshy to do it since. But I did it for a while before that happened without incident. I'm just being a pussy about it.
I have pined 1 mill of TNE into bicep. If the muscle is a virgin its going to hurt like a mother for few days. I have done it many times and it isn't that bad after your use to it. Never done a trap or lat shot.
Bodybuilding is about learning to maximally contract a muscle. It is not about lifting weight. The best bodybuilders in the world are that way because they can contract their muscle harder than you, NOT because they lift more.