personal preferences
brand name Adobe Photoshop is better than GIMP in most categories other than cost
but since i used GIMP consistently over the years when i couldnt afford the Adobe CC subscription (or to get a copy of the old CS packs), i do tend to prefer using GIMP for most work (esp tga work).
if youre familiar with the TW extractor, then its perfectly usable, although i believe no longer available on TW site
if just getting started then one may want to use Mue's extractor instead. but those of use that have been doing it a decade+ will use what we're comfortable with