I'm gonna go with gens 2 to 3, with 4 to 5 a close second. The 3rd gen was when everything started to click. Huge advancements in technology, game design, and audio quality. Just compare the average NES game to the average Atari 2600 game. The differences are like night and day.

Of course, the leap to 3d was also huge. The 5th gen was the beginning of modern gaming for me. It introduced most of the genres we all know and love today.

I disagree tbh, I see next gen where the other two don't screw themselves up and seeing things going back to normality.

Also disagree on the one above all approach to gaming because that doesn't bode well for gamers who simply don't want the system but want other ones instead, when things were neck and neck last gen there were plenty of great games and plenty in number too, I feel you just don't like anyone being on top and you much prefer it where Sony is the only one getting everything and no one else getting anything at all. I find that the complete opposite of competition, the only kind you describe is two dying competitors inching on the ground to feed the 3rd, I hope that never happens at all because that would stifle gaming in general.

And as a final note I see VR on PC taking gaming to new heights and evolving ever more.

Gen 5 was the golden age of gaming. You had great games coming out every month. No other one compares in innovation and quality.
Games were cheap to make back then and that allowed us tremendous variation.

^^
Agreed.

It's Gen 4/5. It can't be anything else, 2D to 3D is the biggest thing that could have happened until they invent the holodeck. I'd say the only other contender is Gen 1/2, I agree with Svenno on that, going from pong clones on dedicated machines to 'real' games with characters, environments and different genres on exchangable cartridges is a huge deal.

Easily Gen 7.  Microsoft's entry in the foray was miles ahead what anyone had ever done.

4 to 5 is the obvious choice, but I think 6 to 7 might be 2nd for me

Clearly 4-5th gen, since 3D became huge, we got analogue sticks and more movie-like gaming experiences.

4-5.

4th to 5th, for reasons already mentioned numerous times.

I chose Gen 5 to 6 since the advancement of 3D graphics to near photo-realism seemed like a pretty impressive eye-popping improvement, but I also agree with Gen 4 to 5 due to the 2D to 3D overhaul.