Shutdown abort or shutdown immediate when session ran out?

We experienced session max out error and the database were pretty much dead and hung.

My question is in this case is it better to choose shutdown abort and startup and then try one more time to shutdown immediate and make it a clean shutdown and try to startup again?

Or, do we just choose to use shutdown immediate the first time? Shutdown immediate is going to be very slow at this time because there are about more than 3000 sessions to clean up.

Any suggestions? Anyone out there have had similar experience before please share what is your method? Thank you very much.