For those who played primarily on Sega's consoles back in the day, which has become your new platform of choice, and what specifically made it a worthy replacement?

The heading is confusing

When I was a kid I was able to play a lot of different consoles because of my friends all had different systems.

I had the Master System, my cousin the Mega Drive, my best friend had the SNES and another friend had the PS1.
A neighbour, which wasn't exactly a friend of mine, but kinda of a friend from my bother, had the N64, but I've had very limited contact with it.

I loved both the Mega Drive and SNES, which were a lot more advanced than my Master System, but when I saw my friend play Digimon World on the PS1, it was really something else.

After my console broke because my bother dropped grape juice on it, the nexy year I had a choice to make and it was easy to pick the PS1, after that it was pretty clear that getting the PS was the best choice to make when getting newer consoles, as basically every game I wanted to play was available there.
And after making the switch, not only the 3rd party support was basically 100% there, but Sony own games became my all time favorites, starting with the obvious one.
My favorite game series changed only twice, from Sonic to Pokemon to LoD.

Also it was so cheap to get PS games here because of the piracy, they sold those everywhere, it was actually pretty rare to find original games aside from stores in shopping centers.

Sega consoles were dead and 3D Sonic wasn't nearly as good as 2D Sonic.

Nintendo itself was ok but it was just really not a good choice as the only system I would have.

Microsoft I couldn't care less about, compated to Sega and Nintendo their games had no appeal to me at all. I did consider the 360 because of the piracy but it still was a lot more worthy to get the PS3 and buy used games and not miss on games I REALLY wanted to play like God of War, Disgaea and Gran Turismo.

So yeah, since a kid it was clear to me the PS had the games I wanted to play and it just never stopped being the case.

I never owned a SEGA platform but I did play my cousins' Genesis and finished a few of the games on it.

Now I got SEGA games across all platforms between Nintendo, Playstation, Xbox and PC.

I didnt even know the Dreamcast existed until right about when the PS3/Xbox 360 came out lol.

Hard to give only one answer. It would be Switch AND PC for me.

I grew up with SEGA, Nintendo and PC all in parallel (My parents divorced, and I had an NES at my dad's place and a Master System at my mother's place, plus a PC at both), so in the end it's more like Sega gaming got absorbed by the other two along the way. I also had 2 Playstations (PSOne and PS2), but since the third one I didn't see the point anymore as it's exclusives were not appealing to me and almost all the rest was coming to PC anyway...

I went with whatever consoles plural had games that interested me. I didn't choose a side. I only own an Xbox and Gamecube that gen as I couldn't afford a 3rd console but in 2001-2003 felt It should get a lot of the same stuff. Not as much as I hoped it turned out and got a PS2 in 2010. 7th gen I ended up with all 3 consoles.

While I have not owned an Xbox console since 360 that's because they have not offered me anything worthy of buying a console over in a decade otherwise I would. If Scalebound and Phantom Dust came out I would have bought an XBO. With MS dropping physical games. I have no reason to buy their system while sure on borrowed time. PS5 and Switch offer me that option.

Last decade it's mainly been Nintendo and Sony for me just because of the offerings from Japan 1st and largely 3rd party. I know a shit ton of SEGA fans jumped to Xbox in 2001 because young immature fans were in the fuck Sony and fuck Nintendo mindset. Some are still in the fuck Nintendo mindset. Over time I think like most people who get older got out of choosing a table to defend. Only idiots do that now.

I consider myself a previous Sega fan (had the genesis for my childhood, and an Atari before that (never owned a Master System).
I did play some "pirate" NES on my friends house (we had a lot of copies in Brazil), and my childhood friend and my cousin had SNES so I played it a lot over there as well but loved Sega way more than Nintendo at the time.
I was itching to get the Saturn (my cousin had one and I played Resident Evil there and Virtua Fighter and loved it), but when I played PS1 on a school friend house I was blowback and by the time I was 15 I had the money to buy my first console by myself (I saved the school trip money I received, got like R$300 and came back with 250, plus Xmas and Bday gifts I asked all in money so I had R$500, due to currency, taxes and grey market - PS only officially released in Brazil after PS3 time - it was like enough to buy 3 consoles in USA probably - this was on January 2000 so 280USD and PS1 was 99USD by that time and very close to PS2 launch) I bought a PS1 with 2 controllers (first model), one memory card and 10 pirate SW (Final Fantasy 9, Gran Turismo and Syphon Filter were there and became my love until now).
When Dreamcast was announced I was also eager for it, but well it didn't launch for a price I could afford at the time here in Brazil and well I had to keep saving scraps of money I got from relatives so well buying a new console took another 5 years (when I got PS2, close to PS3 launch).
The main reason I got PS1 instead of N64 was basically the price of console and SW (PS1 was bootlegged only titles) and that hooked me to Sony for years, Gamecube was similar reason for me to not get and Xbox Og came to late for me to even care. By the time of X360 I considered it (my brother had it and a friend as well), and well since already had a X360 readily available to play and was anticipating GT5 and some other titles I gone PS3 (my girlfriend had a travel to Canada and I was early in my first job so I was able to send money for her to bring PS3 with guitar hero kit and Uncharted, which well I loved =p) and seeing how much MS dropped the ball on the second half of that gen I never looked back on keeping PS instead of going Xbox. Nintendo never fully served me because of the poor 3rd party support and their first party titles being more expensive (second hand market and older games still can pay a lot less on PS), but I did play a lot of Wii and loved the concept and even got Move (and well bought a Wii for my collection) and well I do have all Nintendo consoles and quite some of their best 1st party but it is more for family than for myself.

i could never understand the genesis > snes side of the debate.

I owned all major hardware and add-ons from Sega; although, I don’t consider any platform to be an “home” - but it’s fair to say Nintendo is my go-to for dedicated gaming platforms. But when Dreamcast was cancelled, the other console I was playing a lot of was the PSX - I never got too much into PS2 outside of RPGs and GTA - and I found Gamecube was pretty much PS2 without most of games I wanted to play. The Wii and DS revitalized my love for video games in ways I hadn’t felt in a long time - in some ways, not since the 8-bit era. The Switch is a solid successor to both the Wii and DS.

But, if a company brings out an interesting platform, I don’t care the brand name on it. Although, I have a good idea of which companies are capable of creating interesting new experiences, and which ones are only capable of imitation and iteration.

All of the above. I don't adhere to platforms. I adhere to games. Some platforms have more games I like than others, but I like games on all of them.