This is a useful post to discuss, there is no single answer. Start with the lens, the bigger the glass (lower the f No.) the more light the greater the sensitivity.
Next the ccd sensor. The efficiency of collecting light and converting to electricity. The higher the pixel density, the larger the area, the more light can be collected. BUT there is a physical limits to how small they can be made and how many on the silicon for given size/cost.
Now if there are say 6M pixels on the chip, but their outputs are combined to give say a 2Mpix image there may be 3X more light sensitivity BUT lower res pics.
Also we should remind ourselves that our still cams are SINGLE SENSOR. Pro video uses 3 or 4 large ccd chips for Red Green Blue or Luminance - but they cost a lot more and are bigger and heavier!.
Next the electronic processing. How good the cam circuit amplifies the small signals without adding visible noise. Different cams will use different methods. Don't assume there is one best way, there are often trade-offs.
Back to your camcorder question, have you tried taking still pics with one yet and printing say 13X9? Since they output pics to TV's which you view from afar, you don't need hi res (unless its HD).
So take your 2 still cams (which I don't know). I'll bet they have good lenses, probably reduce res. for higher sensitivity, and have good noise processing?
Hope this helps.