Of Nintendo and Sony's 5th gen machines, which do you prefer, and why?

Playstation one. Much, much, much to the 100000 degree better controller.
Better use of memory cards.
Better graphics.
And a ton of good games.

Although I did enjoy Ocarina of Time, Majora, Ogre Battle 64 and some other N64 games.

PS1.

The N64 had absolute gems like SM64, Ocarina of Time, Goldeneye 007 and a few others, but the PS1 just had wayyyy more games while also having lots of special, iconic games.

When did you purchase it?

I really dislike PSOne tbh. N64 wins by miles imho. I had both when I was a kid, and I barely touched the PSOne. I must say that it has games that I enjoyed (FFVII-IX, Metal Gear Solid and Resident Evil 1-3). But those were the only games I really liked.

Ps1 for me, since it's the one I used and enjoyed the most.

N64 by far. Can't compete with Super Mario 64, Ocarina of Time, Majora's Mask, Diddy Kong Racing, GoldenEye 007, Perfect Dark, and Smash Bros. Those are seven of the best games ever made.

Plus the analog stick and rumble. Plus infinitely better load times.

Squaresoft support alone made PS1 the better console. Add in Capcom, Konami, Namco, and Sony themselves, and there's one hell of a library. N64 had a handful of titles I really enjoyed, but nowhere near the binder of disks I ended up with for PS1.

PS1 for me, amazing RPGs, horror games, racing games. A lot of my favorite games are on the PS1.
I think the N64 library is ok, but inferior.
And, to be honest, I enjoyed Legaia much more than I did Ocarine,,,

No Metroid on the N64 had me moving on to more disk-based pastures. I rented the N64 for Zelda and Mario and honestly don't feel like I missed much beyond that. I even worked in a video store during the N64's lifetime and had access to every game but couldn't be bothered. Smash Bros was interesting, but it wasn't until Melee that I think the series really bgecame special. On the other hand, the PS1 had FFVII, VIII, and IX, Tomb Raider, Tekken 3, Abe's Oddysee, Gran Turismo, Legacy of Kain: Soul Reaver, Twisted Metal/Road Trip, Tony Hawk, Syphon Filter, etc!!! Great times that were balanced out by a truer understanding of the great RPGs available on the SNES.