It doesn't matter, because (as anybody who mastered FF8 would know) GFs are not necessary to beat the game. The only reason you should care is if you have a specific need for a person (like a medic).

Read my post above. However if you want a better reason: junction the gfs that have the highest compatibility with the SeeD member. For example, if Quetzecoatl has 1000 compatibility with Squall, you should junction it with Squall. Etc.