I've owned a MiSTer FPGA for close to two year now. I didn't buy everything all at once and kept adding additional things over time. A few months ago, I finally had the complete setup although there are many aspects of the MiSTer (like analog output) that I have yet to take advantage of. I really enjoy the fact that new cores are coming out every few weeks.
I happen to be a Patreon subscriber to all of the MiSTer developers and it is definitely fun to get early access to things as they happen. I don't know if the Sega Saturn core currently in-the-works is going to be fully-functional or not as that may exceed the capabilities of the DE10-Nano hardware but they are definitely giving it their all.
I really enjoy a number of the arcade cores as indeed I played a large number of them growing up. In my youth, arcade machines were everywhere... at "the arcade", grocery stores, pizza joints, movie theaters, convenience stores, etc. There are also a large number of video game consoles including the Atari 2600, 5200, 7800, and Lynx handheld, Nintendo NES, SNES, Gameboy, Gameboy Color, and Gameboy Advance, Sega Master System, Sega Genesis, Sega CD, Sega Game Gear handheld, Neo Geo, Turbo Grafx 16 / CD, etc. There is also a wide variety of retro home computers including all of the ones I grew up with. It is just incredible.
The MiSTer FPGA is like having a few hundred vintage devices all in one tiny little package that can easily connect to a modern display and controllers.
While a lot of people enjoy creating their "retro experience" using software-based emulators, I really appreciate the whole notion of recreating the original hardware in FPGA on-the-fly. It is simply amazing. Most people don't know what an FPGA is nor that it is possible to use them to recreate the original hardware. Below is the best video I've found where the presenter explains what an FPGA is and how it compares to software-based emulation. He also shows all of the components, many of them optional, and puts them all together. He also builds his own SCART cable for use with analog displays.
I've only used an HDMI TV for the display and they work wonderfully. I'd definitely like to get an analog display setup sometime so I can take advantage of the 2P (two player) Gameboy and Game Boy Advance cores that allows two players to go head-to-head by replicating two handheld consoles and connecting them together with a virtual link cable. You can do side-by-side or top-and-bottom split display outputs on a single HDMI TV but allowing each player to have their own physical screen seems the better way to go. Enjoy the video! Oh, and BTW, IT IS LINUX BASED!