The answer depends on several factors.
Supported platform: Windows
The FinalBurn emulators are specifically optimized for games from the '80s and '90s. The Neo variant is the one being actively developed, so the Alpha variant is only recommended if your machine does not run the former well.
Neo's supported platforms: Windows, macOS, and *Linux natively; Android, Switch, Wii U, PS3, and iOS via RetroArch
Alpha's supported platforms: Windows natively; Android, macOS, *Linux, Vita, and Wii via RetroArch
Some interactive films have not been ported to consoles or computers, so this is the only way to play those without their cabinets.
Supported platforms: Windows, macOS, and *Linux
Some of this system's games do not have ports for Saturn or PS3. This program is your partner in this situation.
Supported platforms: Windows natively, *Linux via Wine
Supported platforms: Windows, macOS, and *Linux
Because the NAOMI line has similar hardware to the Dreamcast's, these emulators also run the line's games. Flycast is the one receiving updates, though its compatibility is hit-or-miss at the time of typing this.
DEmul's supported platforms: Windows natively, *Linux and FreeBSD via Wine
Flycast's supported platforms: Windows, macOS, *Linux, OpenBSD, Android, and Switch
This is a set of programs that run Konami's Windows Embedded-optimized games on regular computers. Be aware that an AMD processor and GPU might have trouble with them. Read bemani.guide and the PC optimization guide to learn how to make a specific game work.
Supported platform: Windows
Supported platform: Windows
Mario Kart Arcade GP 2 and F-Zero AX become more accessible with this hypervisor.
Supported platforms: Wii natively, Wii U via backwards compatibility
MAME tries to be a jack of all trades to varying degrees of success.
MAME's supported platforms: Windows, macOS, *Linux, and OpenBSD natively; Android via RetroArch
HBMAME's supported platforms: