Well Tobirama is more proficient at using Suiton but Kisame got tremendous chakra resrves so do you think he got an advantage over him ?
Tobirama Suiton Jutsus:
Water Release: Water Colliding Wave (Anime)
Water Release: Water Dragon Bullet Technique
Water Release: Water Formation Wall
Water Release: Water Severing Wave
Kisame Suiton Jutsus:
Water Clone Technique
Water Prison Shark Dance Technique
Water Prison Technique
Water Release: A Thousand Feeding Sharks
Water Release: Exploding Water Colliding Wave (and its enhanced version)
Water Release: Five Feeding Sharks
Water Release: Rain Water Shark Wave (Anime)
Water Release: Water Shark Bullet Technique (and its enhanced version)
Hard to say, Tobirama probably created many water jutsus himself and he is skilled enough to create water jutsus that normally requires many hand signs with just one hand sign. We also know Ninjas such as Tobirama, Madara, Izuna and Hashirama are on a high tier than kage level but like how Minato took Tobirama's FTG and improved it, Kisame could have done the same but he's from a completely different country and never mentioned Tobirama as a role model.
So I go with Tobirama being more skilled and adept with water jutsus for being able to preform high ranking ones with few hand signs but as to who have the better water jutsus, for now I have to go with Kisame since she shown more but if Tobirama shows some really impressive stuff then my answer will change.