Kisame is solid, he cancels barriers and mystery's, chakra battery (standard stronger the more chakra he has), and can self heal unless ignited when units die. Hes good at what he does, however I wouldn't consider getting him unless you pick up another event based ninja. The exception to this would be getting Ay the third because of the chakra that Kisame can generate.

Edo Deidera. Ill just say that if you don't or cant kill him. You lose. Whether that is spacetime, gnw, or sage world. He's an overall powerhouse. Ignites on crits, incrases his own crit chance really, standard is pretty strong, mystery hits 12 units. You cant beat that. His downsides include building around him rather than him complementing your team. Every person in your lineup should support him in one way or another. His defensive growths are decent. Some people say he goes down easy others Its hard to kill. He only really gets *n up from full buff teams in my experience.

Shisui, is one of the three that I don't have so I cant say too much. I will say that he is on the strong side. Not broken but very strong. Mystery hits 7 units and can chaos 1 unit for 2 rounds. The only other ninja capable of chaosing that long is of course Susanoo Itachi (who is much harder to get these days). Standard is amazingly powerful. His chase tags (R.I.P to your res and def). My favorite and least favorite thing about him is probably the barrier that buffs 3 elements. That element buff is amazing, lightning, wind, and fire I believe. The downside to this is that barriers staying up is very dependent on who has what in your server or cross server events. So you'll want to plan, and build a team assuming that you wont have your barrier, rather than depending on it for damage output.

I think if I had to choose again I would pick edo deidera everytime. I feel like I bring more to the table with him when its time for war and he carries my spacetime fights as well. But it really comes down preference and playstyle. What do you need right now? How do you like fights to go? Do you want to be in control? Do you prefer scaling and DOT damage? Are dodges something that would be nice to have in your current pool of ninjas? Those are things you have to ask yourself picking up ninjas. Have in mind teams and strategies before you pick them up. Have a team that can counter virtually every team using them. It would really be between him or shisui for me. Like I stated above, Kisame needs other ninjas I feel; event ninjas. But if you find yourself making solid teams without those event ninjas, I would would rank them Edo Deidera, Kisame, then Shisui. Once again this is my preference so maybe Shisui will be better in someones eyes than both of them combined.