Interior Staircase to Basement vs. New kitchen

[Prenn Tran]

Hey Guys and Gals.  I've been following the biggerpockets' forums for a while and have just purchased a duplex.  I plan to write up my new member story soon, but in the mean time, I need some help with renovation decisions.  So the current status of one side of the duplex is a 2br/1ba with kitchen and laundry on the main floor.  There is a basement underneath that is quite large and completely empty.  However, the basement only has an exterior entrance/exit.  I plan to renovate the basement to add two more rooms and rent each room individually.  My question is this, which of the following is the best option?

1.) Add interior stairs from main floor to basement.  This would allow all four tenants to use the kitchen/washer/dryer on the main floor.

2.) Add kitchen/laundry to basement so that the tenants in basement have their own kitchen/washer/dryer.

If anyone has insight on which would cost more, be an easier DIY, etc... I'm all ears!

*Basement has bare walls currently and plan to install a bathroom regardless.

Thanks,

Prenn