Neither
Neither are worth the tier 4 basic (or t2a if you’re talking 5*) save for a better champ
GG isn’t a bad champion. He has a bit of regen and a few other tricks up his sleeve. Long term, SL would be better assuming you could awaken him. I would say it depends on how you’re doing for resources - have you got iso/T4CC expiring? Otherwise I would save your resources; there are other champions far more worthy of your attention in the game.What other tech options do you have? Maybe you have a few gems hidden that you have overlooked/don’t appreciate the potential of.
i'd go with yondu, he's easily the best tech champion that you have, unless you can dupe SL, and even then i would still have doubts on who to rank up: SL can do more damage, sure, but i think that yondu has more utility with heal block, bleed, armor break for bleed immune, ability to crit and to apply debuffs through block, and weakness when duped