The GH gives you more usable third-row space. If you often need to use the third row, the GH might be worth it.
Had a 2012 Highlander, which was totaled. Now we’re using a 2018 Highlander, which feels even roomier. The regular Highlander works well for us, and for big trips, we use a roof box.
As kids get older, their gear takes up more space. Even a small amount of extra room in the GH can make a difference.
Funny enough, the regular Highlander is becoming harder to find than the GH.