G5
If you're considering the G5 or the eMac, and you can afford both, (even without the monitor for a G5) you should definitely go with a G5. The CRT will work fine for you G5, like robbieduncan said, so the G5 will probably leave you much better off.
Of course, this depends on what you plan to use it for. If you are just going to be using Safari and TextEdit, then you should just get the eMac... lol. I'm guessing you'll be doing more than that to even be considering a G5 though. Don't listen to me anyway, I'm sure you've already made up your mind.
Good luck.