I think GG is cool and potentially very good, but I dont see any outstanding traits that would make him a top 3 player. A lot of times if the most exciting thing about a prospect is their age, I dont think they are worth too much hype.
The argument for Flip over GG is that you are potentially getting a Lauri Markkanen type player, a mobile 7' who can be an elite shooter. Right now I have GG over Flip as well, but I wouldnt say it's set in stone. If Flip can show more consistency and really elevate Duke, he could leap ahead of GG, especially if GG really struggles in conference play.
GG's combination of length, athleticism, handle and ability to create space and get downhill make him special this draft class. To me, that gives GG a much higher ceiling and puts him in a different tier from Filipowski. Drafting Filipowski over GG would be similar to drafting Kelly Olynyk over Giannis, imo. Hopefully, Danny Ainge learned from that experience.
If you want a big who can shoot and facilitate, then Filipowski becomes interesting. However, the Jazz already have a better player in Lauri and could draft an equal or possibly better prospect in Baba Miller. Miller should be a multi-positional defender and would be a better rim protector if he'll commit to it.