Character Maker 1999 (2K3/XP/VX/VXA)
Character Maker 1999 was (and still is in my opinion) one of the most definitive RM2K/3 resource editors of its time. All of the resources can be edited or created anew. This is a tool I've used countless times and one I will be using again and again.
This editor can also be used for editing RMXP, RMVX and RMVXA resources, but it is limited to 256 colours only. The colour depth can easily be increased in modern graphics editors and imported into RPG Maker. This might be a long-winded, and maybe unconventional, way of editing and creating resources nowadays, but what I like most about Character Maker 1999 is the simple fact that you can change the size of the cursor according to resource image specifics, which reduces misaligned positioning and makes life easier in general.
Personal Note: I'll do a thorough tutorial review some time later.