In addition to the suggestions posted, it would help if we had an idea of what your budget was. With that info, you could get some specific camera/camcorder suggestions that could produce the best bang for your buck. Most people on this forum (as a collective) have experience with equipment running from a couple hundred dollars to a few thousand dollars, so there's usually someone who can chime in on the subject.
But yeah, manual focus is probably the biggest thing to make sure to get. HD comes on just about everything nowadays, whether it's 1080p or 720p (you'll want to get 1080p if you can). 4K is nice if it's affordable and practical, but isn't really a necessity yet. "Good in low light" definition varies depending on who you ask, but generally a bigger sensor will do a better job. For memory storage, SD or CF cards are the standard for most people (usually the best options for the fastest workflow). I prefer a good SD card with fast read/write speeds myself. Most of the time you'll be fine with something like 16 GB of memory on any given day, unless you constantly have the video recording. My full 1080p memory usage at the end of any day from my camcorder is always (almost always?) under 8 GB, but I shoot mostly in shorter (3 min or less) clips unless there is actually something worth shooting longer and/or I'm shooting a time lapse. Internal memory storage is fine, too, but it's good to have the extra slot for an external memory card just in case.
