AIIB progression has been great and it's harder to join AIIB now.

http://en.people.cn/n3/2017/0522/c90000-9218670.html

AIIB has many projects to invest in especially the one-belt-one-road initiatives.  AIIB will start to be profitable soon because many of the projects are government or state ruled with low bankruptcy probability.  It's harder to join AIIB now because many existing members don't want their shares to be diluted.  Not many countries are willing to give up their shares in AIIB and late comers will have little say in AIIB.