Getting serious with FPS's again, help me pick a mouse!

So I've always been an FPS fan but since WoW came out, MMO's have been what I choose to push to elitism so I have a house full of Nagas ready to be used with where-ever I decide to plop down with my laptop for the evening. When I DO feel like playing an FPS, my nagas tend to do well-enough of a job for me. Last night, however, I found myself struggling to do 360 degree spins while maintaining accuracy when playing Vermintide 2 and Overwatch. To the point it consistently ruined my fun. Soooo now I need to buy a mouse dedicated to FPS's. The last time I truly cared about precision and consistent accuracy was the CS:S days. Since then, holy crap, mice have come a long way. The tech is advanced, everyone has their own type of grip, etc. So I have some things to figure out. I don't know if I use a claw grip, if a lighter mouse is actually better for me, etc... With that said, I'm deciding between two mice right now. 1. Razer Viper: Obvious contender for obvious reasons. 2. Razer Mamba Elite: This one felt best in my hand at the store when I was at Best Buy last weekend. It's most reminiscent to the original Razer style that made me fall in love with the brand many years ago. It's 30g heavier as well. Bonus: $30 cheaper on Amazon Any advice?