Need suggestions please!

hasoonfcb

Hey guys, so i am currently lvl 60 and have the following partners.Toshiro Hitsugaya (Vanguard )
Yuroichi and shinji (Assulters)
Retsu Unohana Kenpachi (Support)
and my zanpakuto is senbonzakura (bankai atm)

I just want ur opinion on something, firstly is byakuya tav. worth getting to compliment senbonzakura. and secondoly, what do you think of replacing shinji with another assulter, any suggestions on who. and i was thinking of grimjow from swp. Any suggestions are highly appreciated!