Anyone have a preference or thoughts on which may be more effective?
Difficult to answer. Both if you can afford it. CoQ10 is a powerful antioxidant and Arginine dilates blood vessels, improving blood flow to the penis.
Personally, I use Citrulline Malate instead of Arginine. It's more bio available. If you Google the subject, you can read for yourself.
I don't understand your question Ketric
L-Arginine and CoQ10 are very different, acting very different on our body, they are not VS each other.
As Jonbinspain, per NeoV advise, I am taking L - Citrulline Malate instead of L-Arginine that didn't helped me with nothing in the past.
Waiting for results.
James