TV:
- TOS
- TNG
- The rest (haven’t seen but a few episodes of any other series, none look very intersting).
I would suggest watching DS9 if you at all liked TNG. It’s a really good series… until the last season, in which it gradually starts to suck, and the finale is the epitome of sucking for the series. So, just watch the series until that point, and then either prepare yourself or stop watching altogether.