So we have the two best water style users in NV history against each other.
Kisame
-All techs that he has are allowed
Tobirama
-Since Kisame has Samehada its only fair to let him be an Edo Tensei
I personally believe that Kisame might win
Why weaken Tobirama by making him Edo Tensei? Alive Tobirama>Edo Tobirama but either one takes this. With FTG, Tobirama dodges everything Kisame throws at him and for water Dome he can FTG out or he can teleport the dome away. Tobirama have faster base speed as well, he rushed Juubito with Hashirama's clone and not only put multiplying exploding tags but also tagged him with his mark. Also samehada isn't loyal to Kisame, if Tobirama has a better tasting chakra than him then he would ditch Kisame for Tobirama as it did with Bee.
A great way for Tobirama to beat most people is to fill the field with water (which is made from his chakra) then he can FTG anywhere his water is and can teleport whoever or what ever the water touches. Just like how Minato can teleport Sasuke and Naruto just by Naruto connecting them all and Tobirama used Minato as a medium to FTG SA members who Minato and Naruto gave chakra to so he can teleport others if they touch or connected to his chakra. FTG Kisame to him as he slash Kisame. He doesn't have to FTG Samehada like Minato didn't FTG Juubito.
Differences is that Bee didn't want to be noticed and held back against Kisame. The 8 tails out right told him to just go full BM and make the water dome into nothing. A tbb kills Kisame neg diff. The MS user wasn't holding anything back and was much stronger than Kage level as Izuna, Tobirama, Madara, and Hashirama are all above Kage level.