Z2 is very grippy, much more than G-1, it also feels softer.
Z2 is the first rubber to ever feel like Tenergy to me (I mean that!) but softer feeling and more forgiving, kind of in between Tenergy 05 and 05 FX in terms of hardness feel. It has that special thing Tenergy has that ESN has never gotten (although I have to try V>22 again, it gave me Z2 vibes but I could be wrong, still have to really test it), not that this makes ESN rubbers bad or anything, they're different and many players prefer them.
G-1 and the Fastarc series are very straight forward oldschool ESN's like Rakza 7 and Barracuda, no nonsense, very good and stable without the factory boosting that wears off. Z2 is more dynamic and has excellent feel and still doesn't have the factory boosting.
I think Daiki has finally figured out something only Butterfly had figured before with Tenergy and it's exciting!
To answer OP more concisely (too late!):
- Z2 feels lighter than G-1
- Z2 might be slightly more linear than G-1, if so, not by much, I can lift the ball or generate spin more easily with Z2
- They're both as comfortable close to the table but I prefer the feel of the Z2 so it seems easier
- Z2 is great at driving and flat hitting and fast, better at hitting than G-1 as a result, but that doesn't mean it's worse at looping (i think Z2 is better there too since much more grippy and dynamic), and G-1 is still good at both too
- G-1 is more stable and more forgiving, no doubt
- I obviously choose Z2, it feels better to me, softer (without being mushy), more dynamic and special without being crazy uncontrollable or spin sensitive
Hope this helps, I usually don't sing such high praises for a rubber, and the Fastarcs and Rakza 7's are typically what I recommend the most for intermediate players, but I think Z2 is top notch for high intermediates and higher.