Gol is a special case, it is semi-LCC, but is also the dominant carrier by far in Brazil, and now that it is eating much of what was Varig, is becoming the primary Brazilain int'l carrier. All the alliances are after Gol, so that is not a fair comparison.
Regarding what are, and what are not "quality partners" is in the eye of the beholder. I have heard newbies on FT bleat on for years about how "there is no Australian/Oceanian partner in ST". Well, Qantas and AirNZ are spoken for, so its sort of tough to get anyother major partners in those two countries which have a whopping population total of 25 million or so. Not very experienced people s...... at Aeroflot as a member, while those of us who actually have to fly to Russia, not only appreciate the service, but know for example that Aeroflot Europe services in Business Class beat any and every other European carrier.
The only "quality" airlines left are the Gulf carriers and for a variety of reasons none of the larger ones will be entering an alliance for quite some time.