"Money isnt much of an option" means you have big budget right?
Well the G4 is the easiest for aesthetics and ease of installation. It may not be the best, for aesthetics, or performance, or ease of use (I dont have one), but it sure is the easiest, and as such is marketed as one.
With that said, there is very little you can do to improve it, or expand it. It is low power both on consumption and performance, but it works.
If you arent good with fabrication or cant get someone to fab a screen into your dash, then a double din solution may be best. You may want to follow the double din case thread, because it is sort of a "roll your own" G4.