MiniDV is the way to go nowadays. If you have your heart set on 8mm I would go digital. What really effects quality is how many chips are in the camera. The top quality ones use 3 CCD(chips) A 3 chip uses a different chip to capture the blues, reds, and greens. A cool website is [url]http://www.camcorders.org/[/url], might help you out.
I have a panasonic PV-DV951. Compared to my old Sony HiFi-8 the battery lasts forever though it is probably due to battery improvements.
I just got a Sony TRV840. Digital 8. The battery which came with the unit lasts 90 minutes. 1/2 of what it can with normal 8. The tapes, you can buy cheapo ones and they look just as good as the digital 8 tapes. You can get two for about 6 dollars. Mini-dv tapes are more expensive.
I'd get the best optical zoom I could. Mine is only 15x but you can buy an optical 2x adapter which = 30x. The digital zooms pretty much suck.
Btw, my 840 makes a loud noise indoors. It is the tape spinning and the microphone picks it up. Outdoors, you can't really hear it. So, if you take lots of indoor movies, make sure you test it out with the tape going.
Also, the quality of my 840 is outstanding.