Anyway, as suggesting just names ain't the best option, I'll provide you a detailed report to my suggestions as I got some time off before I go back to my studies.
Firstly as GFX Moderator I strongly recommend and believe that the most suitable and currently skilled person who hasn't his chance yet is xDamian. Browsing his DeviantArt profile you can see some impressive stuff uploaded. Also there are some examples of his amazing work shared in MaxCheaters too. But the fact that he participated and won several times the "Signature of the Month" competition as they were organized by the current GFX Team is the best piece of evidence that he's currently the best GFXer of the forum. (Apart the team). Also he can speak English & he's mature enough to judge any situation that occurs. (http://xdamianart.deviantart.com) Another option would be Voqus who got skills & awards during the SOTM events. Also he can speak English very well.
As Gold Members I'd suggest Universe but I won't. Although, he tries enough to be back, I don't believe that he suits to such position. I believe that he's weak to judge fairly and also he can't communicate very well with the community as he lack of English knowledge.
My recommendation on this rank would be Matthew. He's active and polite, he can speak English, he's "fresh" and also I believe that he's mature enough to take decisions of moderating.
Zake should be back as a Global Moderator. He was doing an excellent work over here and I still don't know why he was demoted by he deserves to be back. He deserves a second chance. His skills were proved, he did well, and he was active & mature enough to be there.
Last but not least, the most suitable staffer (in any rank) would be Elfocrash. Although he's an ex-staffer he proved his skills. His English level is high and he is capable of handling the community. So obviously, Elfocrash deserves a higher rank in here.
From current staff, probably Nicolas would be worth a shot as Global Moderator. Active enough, he has gain enough experience to have his chance in a higher position.