A numeric score for a system? How very... odd. I don't think I can go back to that sort of mentality, to be honest, so I'll go for pros (+) vs. cons (-) instead. That better illustrates my own values for systems versus what a simple numeric score would tell you.
NES:
+ Plenty of games I like
+ Easy-to-use controller
+ Fast load times
- Controller is uncomfortable to hold
PS1:
+ A solid library of games I like
+ Relatively easy-to-use controller
- Long load times
- Unreasonably small storage space for save files
PS2:
+ Many games I like on it
+ Relatively easy-to-use controller
- Blatantly an incremental upgrade of the PS1
- Long load times
Wii:
+ Plenty of games I like on it, and more coming
+ Very easy-to-use controller
+ Usually pretty quick load times
- Memory space for save data and channels is a bit small
DS:
+ Many games I enjoy, more coming too
+ Long battery life; rarely goes out on me sooner than 8 hours
+ Well-made and convenient controls
- Not as portable as the GBA SP
PSP:
+ Decent library of games I like
+ Workable controls that have few major issues
- Low battery life
- Long load times
- Not as portable as the GBA SP
In case it wasn't made clear before, these are based off of my values. So if you don't agree, don't panic. That just means that your values differ from mine, and that's quite normal.
Sky Render - Sanity is for the weak.