The quality of texture compression depends heavily on the kind of data. So asking for a "better one" is too broad. Is it for color? If so, is alpha included? Is it for normals, and in what space? Is hardware support required? And on what platforms is it needed? ...
A coupe of other compressions methods for textures I know of, for the one or other use case:
* DXT5nm - Normal Compression
* 3Dc / BC5 - Normal Compression
* RXGB - Normal Compression in Doom 3 (EDIT Well, not sure whether this can be called an own compression.)
* ASTC - ARM Adaptive Scalable Texture Compression (on some mobile devices, AFAIK)
* ETC1, ETC2, EAC - Ericcson Texture Compression (on some mobile devices)
* PVRTC, PVRTC2 - PowerVR Texture Compression (on some mobile devices)
* VQ - Vector Quantization (no hardware support, AFAIK)
EDIT: I see now that the thread is tagged with [D3D9]. Regardless the DXT compressions "misused" for other purposes than originally intended for, I think there are no other methods available.
Edited by haegarr, 11 October 2013 - 01:27 AM.