In my opinion,
Lens filter diamerter larger than 70mm.
3CCD (or 3CMO) imaging chip system 1/3" or larger.
Audio input jack.
Manual audio gain control on the outside of the camcorder.
Manual focus ring on the lens barrel.
Separate manual zoom ring on the lens barrel.
LCD panel and eyepiece viewfinder.
Low compression captured video format (DV/HDV, DVCAM/HDCAM, DVCPro/DVCPro HD, etc...) No AVCHD.
A good example is the Sony HDR-FX1000.