5* Aizen! Build Question

Hi Guys! So I finally got hit with some of the RNG goodness. Right now I am sitting on BIchigo, Shinji, Aizen, and of course Renji.

I also got the 4* Aizen in the same drop so I have the possibility to make Aizen 31% dodge rate if I lock Shinji to him in order. This would force me to continue to use Renji but I could lock a 3* Chad and full defensive gear will lock him in as a tank long enough to get my next 5*.

Is this a good move. Should I continue to use Shinji instead of powering up Aizen? What do you guys think? I have 400 medals so by the end of the month I will get my next 5* regardless of what they change the characters too.

• Edit Changed Sanji to Shinji because I am dumb....