Hi there, I use an ASI224MC exclusively for planetary, it's probably the best bang-for-buck colour camera out there, and still used by C14 owners. As John says, the ASI290MM is probably the most commonly used mono camera for planetary and while I'm sure it will produce a better result, it's a
lot more effort to capture and process the images. Motorised filter wheels, 3 video captures required instead of 1, more processing to de-rotate and combine them together, etc.
Is it worth the extra effort? Have a look at Darryl's (aka Kokatha Man) website, he uses both the 224MC and 290MM to good effect.
http://www.momilika.net/WebPages/AstroIntro.htm
Andrew