Well, I guess that the most important thing to know before choosing, is how you want your game to work and look.
Different RPG makers have different style in the tilesets, characters etc. It also depends on if you want to have script in your game. Editors below XP haven't got any script editor. XP script editor uses RGSS while VX script editor uses RGSS2.
I checked what scripts and resources there were for XP and VX before choosing.
Myself I'm using XP since I don't quite like the VX style.
That's the most important things that comes to my mind.
For the first game, I don't have any plans to do any scripting. But my second game will probably have some script in it eventually. As for the looks of my game, I like the old Rm2k RTP, but XP doesn't seem that bad either.
Oh, and thanks for reminding me about VX, Ill be sure to look into that. I don't know anything about VX however, what are the advantages/disadvantages of VX vs XP?
Im beginning to think I might do XP/VX simply because if I make a sequel to my game, it will be more advanced and may require the use of scripts in a few ways + whatever other features XP/VX has.
So I guess the question now is, VX or XP? Your thoughts?