YoshiKyon

Okay, disclaimer that I almost always have a ton of recency bias - I spent years playing things like Pokemon & OOT randos, and loved them at the time but burned out on them (and have come back to them since, but it still hurts what I think of them).
Also gonna break each part of this into two, since there's a couple of ways to interpret these and it gives me an excuse to ramble more about rando stuff~

Favourite rando to play: I think it's safe to say this is Final Fantasy 4: Free Enterprise at this point. I've been playing it on and off for about 3 years now, and only recently got involved with the community which is incredible, and that definitely helps with the enjoyment. Mostly, though, it's a series & game that I love, and a really open-ended randomizer that gives you enough options to feel like you usually have big decisions to make, but isn't so big that it takes forever or that it feels scammy when the item placement sucks and you lose to that¹. (It's also really easy to learn! I've got so many people who'd never even played FF4 into this rando~)

Favourite rando to watch: I'd probably say Wind Waker. The tourn rulesets and such allow just enough glitches² that it feels like every race has new tricks (and that always feels fascinating, even if they're relatively trivial in both difficulty and purpose), but not so much that it feels completely inaccessible to newcomers. It also has so much freedom in routing that it's rare to see both runners follow the exact same route, which makes for a way better viewer experience than randos that are smaller or have clear-cut best options throughout.

Most memorable run (gameplay): Rando runs tend to be memorable for two reasons: either they were relevant for some particular reason and the seed itself doesn't matter, or they did some wild stuff with the logic³. I can definitely recall some incredible races I've commentated or watched more than played, but the best was definitely the OOTR S3 finals. Marco and Bonooru were almost undeniably the best two players in the community, had already played in Winner's Finals and finished 11 seconds apart, before Marco won in Loser's Bracket to make it back to Grand Finals. The S3 meta had been basically solved by that point, but the seed was interesting enough to provide a few big differences, with Bonooru reaching Ganon's Castle first, about 20 seconds ahead of Marco - and then fell into a pit and voided out, costing a bunch of time. It ended with a 10 second difference, and the post-race interview was just unbelievable. Both knew each other well enough to predict the plays they'd make, to the point of both essentially reciting the other's route in the interview.

Most memorable run (sentimentality): There are a couple of options here from the first OOTR Multiworld tournament; it was responsible for me making a ton of friends in the community & we had an incredible underdog run, but the only race that really stands out there was our first one, mostly because it was a big-name streamer's team, but it was just the starting point of a good run more than that race being especially good.
Instead, the recent FF4FE team tournament was a fantastic experience - the format made it a ton of fun to talk with team-mates, even with varying skill levels, and we started fairly slowly (2-2 in matches, 6-6 in individual games) before running off 4 consecutive wins (including against two unbeaten teams) to make top 4. The individual game, though, was in the third-place playoff, where it just felt like everything I'd learned over the 10 weeks came together in one fantastic race where... both me & my opponent full-cleared the game, but I managed it faster. More than anything, though, it felt so good to feel like I could pay back my team for all of their wins & all of the help and support they'd given me throughout the tournament. (I'd won a couple of games in the tourn, but this was the first one that really felt like it made a big difference.) (Also I did comms for the rest of my team's races a couple of days later and it was probably the most fun I've ever had on commentary~)

1. A lot of people in rando circles hate this line of thinking, because "it's a randomizer, why are you mad about it being random?" but there are levels to it. Personally, if I feel like I'd have had better or the same results with just random dice rolls instead of any real decision making, then it just feels like wasted time.

2. The randomizer is set up to not require glitches to play, but since the tournament scenes allow them, pretty much everyone who races will end up learning them, at least. There'll always be people who don't like the glitched side of speedruns/randos, but I've always loved watching it, I just don't have the patience to learn them generally.

3. For non-rando players: each randomizer will typically have logic to each check that dictates what's required to reach it, and thus ensures any given seed is beatable. In the case of Zelda randos, the worst-case scenario for dungeon keys is assumed, which especially leads to some weird situations in OOT's Spirit Temple, where you can have adult-only items required to open chests that you can only reach as a child at the time.