I've got REX, complete UTX, complete FSG, ASE +XG and Autostar. I had GEX but thanks to Flight1's return policy I was able to get my money back. That's only the second time I've ever returned a payware program.
Out of the bunch my usual standard load is full world FSG Mesh, Full UTX, ActiveSky Evolution, XGraphics and Autostar.
I've re-installed REX a few times. The first time was a stand alone REX install with it taking full control of the weather and textures. The last time was REX textures but letting ASE handle the weather generation.
I'll try REX again when the new texture pack comes out, but for now I keep gong back to ASE + XG.
FAC