We all have that deck that just survives even though it isn't the best. For me that's [[Torgaar, Famine Incarnate]]. It's not the best mono black commander in any way but its particular combination of effects to me is emblematic of mono black. It's a bit of a swiss army knife and so I find myself hard pressed to really change anything about the core of the deck.
My oldest deck is [[Aesi, Tyrant of Gyre Strait]] which has turned into a bit of a monster since I added a few cards that happen to create a bunch of ways to make infinite Landfall combos. It could probably be even stronger if I took out some of the high-cost sea monsters to focus just on Landfall, but I like big sea monsters.
After that my [[Gishath, Sun's Avatar]] deck is pretty new, I just made it this year, but I already love it. Big dinos!
I built a [[Multani, Yavimaya's Avatar]] $50 budget deck a number of years back that is just a mono green spell slinger build. It is pretty simple to play for new people and resilient enough to play with my normal group.
Being a budget deck I even run it unsleeved and get that nostalgia of playing kitchen table magic as a kid.
That sounds great. I care about the new player experience as well and it's cool to see such a "what you see is what you get" commander get some love. I need to pick one up, actually.
I've almost always had some sort of durdly artifact deck built. Started with Kurkesh "Tinker Toys" where it was just a bunch of things that could fit together into whacky Rube-Goldberg machine combos. Eventually moved it to Breya when she released and the deck became much more powerful and streamlined.
Later on, I put together Osgir + Zirda and also Urza, Lord High Artificer, featuring mostly old-bordered artifacts and pre-BRO cards that reference him as a character. I joke that the deck is about a 4 and 3.5 of that is Urza himself.
Nowadays, I've achieved my final form and I'm playing 5C Legendary Artificer tribal with Ramos, trying to recapture some of that weirdness of Kurkesh. Has been a fun time!
This is the only commander deck I've consistently kept around over the years. I don't remember how I discovered this card, but I think it's a neat ability and the commander itself feels flavourful and badass. I started playing during Return to Ravnica, which perhaps added a bonus feeling of "wow, it's the original Isperia!".
My deck isn't terribly good since I don't play Commander very competetively. I've tried to have sphinxes and stuff that feel badass and fitting for the deck instead of busted combos or whatever. [[Medomai the Ageless]] is a typical target to search for.
The only "combo" I can think of off the top of my head (been a while since I've played the deck) is [[Bruna, the Fading Light]] and [[Gisela, the Broken Blade]]. I think that combo is hilarious due to the name of the melded card: Brisela. We ship Brisela.