First 3D gen and it's not close.

Gen 5 is nearly my favorite of all time. It aged relatively poorly but I value generations mostly on how they felt at their time.

HD gen is my least favorite: Piss filter, unstable 30fps everywhere (a downgrade from gen 6 where 60fps ruled), smaller generational leap, relatively minor mechanical improvements (Gen 5 was a revolution. Gen 6 was a huge upgrade), Japanese devs struggling (particularly Capcom, Konami, and SquareEnix), dudebro games taking over, longer loadtimes, etc. But of course it still had plenty of great games to make even the grumpiest happy if they bothered digging. All generations 3rd and up had amazing games

DK64's not a bad game, but it leans too hard on backtracking and an overload of collectables to be truly great, whereas Tropical Freeze is in my opinion one of the greatest 2D platformers ever made.

Yeah I did love the excitement and explosive creativity of Gen 5, where it felt like every few months something new came along that was unlike anything ever made before and revolutionized its genre.

Gaming was more mature by Gen 7 so there was less room for such upheaveal, though we did still get a ton of amazing new IPs.

Frankly, I'm a bit torn as to which I think was "better".

More revolutionary? The first 3D gen, of course. So many new gameplay ideas and analogue control becoming a standard (and rumble) but like people have said, it didn't age particularly well. Ironically, I probably hold more 2D games on the Playstation (and definitely Saturn) in high regards than 3D games, with the Resident Evil series, Tekken games and racing titles being among the exceptions. Polygonal games on the N64 fare better and I will say that, considering the technical limitations, Nintendo produced some really fun and engaging designs with things like Mario 64, Wave Race and Zelda.

But the HD generation complimented the rise of high definition TVs quite nicely and huge, sprawling interconnected worlds were very welcomed. Getting to play PC games like Elder Scrolls at that level on console was fantastic. There were a lot of generic shooters and dull colors though for sure and I definitely agree with @Kyuu that going from so many 60fps titles during the 6th gen to the stuttering 30s was very disheartening (although the frame rates of 5th gen games were even worse) but we still got some pretty smooth playing stuff like Modern Warfare at least (before COD had worn out its welcome). And I must say, something like Bioshock just wouldn't have had the impact it did on me if it had been delivered on lesser hardware at standard definition, not to mention the Uncharted series or The Last of Us.

Personally, I very much enjoyed both of these generations. In fact, I'm likely in the minority here but I much preferred the industry in general during both of these eras than Gen 8. The PS4 was pretty good, but Xbox One, WiiU, 3DS and Vita all contributed to a generation I don't look back on too fondly. In any case, I voted for Gen 5 simply because of the gameplay advancements but it's still close for me.

For me, 3D invented something entirely new, whereas HD just made what was already invented look clearer.

HD. Controls, especially in relation to camera, were often just awful in the first 3D gen. Overall quality was just much higher in the first HD gen. Nostalgia is the only reason I could say otherwise, so I won't.

This.  I can play N64 with nostalgia glasses but those games were and are still rough.

I feel the first gen of 3D has aged badly apart from a few N64 titles . whilst the early HD era has games that still look great today. I played max payne 3 recently and It looked superb, and the gears of war titles (with fps boost granted) on xbox still shine.

Both were bad ideas, but HD was less horrible than 3D.

Pretty close poll, seems like this is one that people tend to feel strongly about one way or the other.

I actually find it a tough call personally, I love the N64 and PS1, but I love PS3 and 360. The latter are definitely easier to go back to today, but at the time, the former were arguably more mind-blowing.