Well to be honest the super 6 is nothing new, it's a nice looking pv really slick and sleek purely mechanical which is good for durability but that's it. If you got a GG then I don't think a super 6 is going to change your world.
The mako.....let's just say if you want something that you will have to play around with forever and you like your PV to be really annoying then it's a good option, it's a good PV but it is not user friendly.
The double barrel silver bullet, now I own an omega and I love it, silver bullet is same thing just a bit bigger and a side switch. Double barrel seems like it's a bit too intense but I guess for some people that might be what they are looking for. Just as a note this is just for the top cap you still need a regular silver bullet sleeve to put the cap on to so to me that's a drawback.
If i had to choose out of the three I would say the DB Siver bullet. I would look into a variable voltage mod like the one pro vape is coming out with soon. It looks so damn cool.