some authors go on for 40 pages...others have one page and THAT is their chapter length. Whatever works for your flow is what the length ought to be.
my chapters are between 15 and 20 pages long (which is about 3500-5000 words)...I can get a wordy at times and I only let the length of a chapter get a way with me if it really works. I'm trying to keep them around the 15 page mark for flow. Any more is dragging the story down.
If it's fast paced and the reader needs to go go go, short is good. If it's Gone with the Wind...long descriptives....long is good.