I actually get this a lot and it ultimately comes down to adherence.
What you can ACTUALLY stick to?!
If you think you can do 5.. possibly...maybe... Don't set yourself up for 5 days. The chances of sticking to 5 days (while that sounds freakin impressive) is probably slim. Stick to something you can actually do and don't set yourself up for failure before its already begun.
For me I train 4 days. 5, I couldn't commit myself to, so I don't do it. Imagine the feeling by the end of the week, (and constantly every week) your program is only partially completed. Not good..
Now imagine the feeling at the end of the week, when all the days you were scheduled to complete your training program you did!
I'd say the MINIMUM amount of days per week to train would be 2 and obviously more the better. But stick to what you can actually do within your lifestyle, not hope for.