Regen will cause redraw but its still nice.
Willpower became even better in i13 thanks to the defence bonus changes and now you can cap f/c/e/n while maintaining high regen and hp.
So what would you suggest I should take?
I found that DB/Regen lacks a certain ammount of mitigation. All of DB's knockdown is at the end of relatively lengthy animations, unlike other primaries where it "Wham-Knowdown", DB ones are something like "Ping-Ping---Ping-Knockdown". Between the "Pings" the Chief Soldier gets to run you through with a sword twice your size. Regen tends to suffer under that exposure, at least it did in my experience of that combo.
Willpower would provide you with better protection in the long run because it covers more bases defensively.
Ok well I already have a lvl24 DB/WP ill give it another go and see how I get on with it, if not ill just re-roll 
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Ok so Im going to be making a new DB scrapper. Problem is, im not sure if I want regen or willpower. Something is telling me go for Regen, but I kinda want to no whats the difference? Also some people have been saying that DB/Regen can be a right nightmare due to trying to make the combos but still trying to heal, etc etc. So I just want to what would be better iyo