I know I'm late to this, but all it depends on is what you want.

Both are very good units however Shisui [Susano'o] BTs is the best unit currently (until Guy [Gate of Death] picks up more steam). I prefer 6-Paths Pain because he's more fun for team building and Shisui IS a majority of team building which makes Shisui very stale to see and use after a while, but it's a matter of preference. Both are good choices. Go with your gut feeling.

Hey, thanks!

I have a question...
I often see pain doing 10 auto attacks vs me while I only applied 2 debuffs on him, how is this possible? :D
He for example did 4 attacks. I didn't attack him at all or didn't apply any debuffs, enemy main attacks, and randomly this Pain starts doing another 6 auto attacks.
For some reason I can't find out why Pain seems to do so many auto attacks. It even feels bugged being on receiving end like that, lol

Pain easily defeats Shisui with no difficulty. He has the Rinnegan which allows him to use all of his abilities and even capable of destroying the village in a single push.

Some of you will say Shisui can cast kotosmatsukami but this will not work on rinnegan. Then again some of you will say Itachi in his edo tensei was able to defeat pain with his mangekyo . This was because Itachi discoverer his blind spot as nagato was handling all the abilities of pain single handedly. That will hardly work against six paths pain. The only way to beat pain is rinnesharingan (sasuke), sage mode Naruto or six paths Naruto. No one else can beat pain. PartyCity Feedback

And only white mask Obito can beat pain since he has rinnesharingan and Senju cells. To beat pain one should either have a huge chakra reserve along with sage mode or rinnegan

Hey, no problem! I apologize that this response is so late, I'm currently on vacation but decided to check in on forums.

Pain-Tendo [Six Paths Rinnegan] is a weird unit. He gains more attacks from non-traditional debuffs, whereas most other standard attack units gain their attacks from statuses or kills, 6-Paths Pain can get a standard attack from any form of debuff. If you have a unit that applies a non-status related debuff on an opponent when hit (I.e. "Units attacking Shisui will have their Critical Rate reduced by 50% (not stackable) until the end of the round.") then 6-Paths Pain will nullify that reduction and, even if it's not stackable, continue to "receive" that reduction. At-least, that is my understanding of how he functions.

I have used him rather infrequently as my server avidly uses Shisui [Susano'o] 4* so I tend to use him as well to counter being KO'd round 1, so I don't have any clue if he actually does nullify these stat debuffs in any way, but I do seem to get critical hits with him as much as other units when fighting Shisui so... take what I said above about nullifying stat debuffs with a grain of salt. Standard attack units in general are weird, sometimes I have only applied 1 or 2 debuffs to Shisui and he will attack 5-6 times, someone more interested in these systems than myself will have to answer these oddities but this is my conjecture based on what I know.

Hope that helps!

definitely shisui my friend there is nothing to think about

kodi nox

Skillbroken Shisui is the ultimate ninja in game these days. If i had the choice i would go for Shisui 4* and BTs

Definitely 6p pain. Shisui is now easily counterable with irrem standard block debuffs. Pain can do 4 mysteries in 1st round that can nuke enemies easily + even if you beat him he revives and spam shinra tensei multiple times. Also he still doesn't have BT so once he gets it he will be even more OP. I would say even ashura full BT is now much more annoying than shisui.

get shisui, he will carry you for a long time.