If you want to program the game yourself, Haaf's Game Engine(C++) is supposedly good, but I've never used it personally.

If you want a program like RPG Maker that does the programming for you, but just want more flexibillity than RPG Maker, you might try GameMaker. It's fairly flexible, although at first glance it can appear limited.

There is also ika, http://ika.sourceforge.net

There is the Sphere game engine that was is supposed to be made for RPG development, although it looks more like a game-oriented &#106avascript IDE to me... Also it seems to be dead. RPG Maker XP and VX probably killed it since they use a scripting system AND are easy to pick up for beginners unlike free RPG engines like Sphere, IKA, Verge, etc...

There is also RPG Toolkit but I really can't suggest that one. Unlike Sphere, Ika and stuff, it is specialized in JRPG development and the only thing you have to script is the event triggers, but that thing is the less user friendly interface I've experienced besides GIMP and emacs. It is messy and buggy. It has inherent support for isometric graphics, but like everything else, I suppose it is sloppy and glitchy. Like I said, I really can't suggest RPG Toolkit. I'm mentioning it for completeness.

Unfortunately for you, RPG Maker XP and VX are the best RPG development software. If you're rejecting them because it's a "kid's engine" then you should seriously reconsider. If there's one thing I learned from all my time GD'ing, it's that the players don't give a flying *beeeeeep* how the game was made. Unless you want to use isometric graphics or advanced graphical effects like 3D, deformation, "mode7" (I know these can be done with RPG Maker but it is too slow) you should use it.