DarkBASIC Professional is the most advanced games development package built on the BASIC language currently available. No other package out there makes it as easy to incorporate all of the special features and effects you see in todays games and no other package natively offers the benefits of Microsofts DirectX 9 technology.
I have been using TGC's DarkBasic Pro (and DarkBasic Classic before it) for almost 6 years now, And although I have tried out other engines and languages, none seem to match DBP's balance of power and ease of use. It is also fully expandable with an array of plugins available to use, both official ones released by TGC and also third party ones created by TGC's community. Both of which are almost always of an extremely high quality.