I really liked Burger Time. I felt like it wasn't mind numbingly hard and it was a good value proposition for a quarter. I similarly feel the same way about DigDug.
Spy Hunter was a revelation. But really hard.
Seeing Dragons Lair for the first time was mind boggling. But I sucked at it.
Street Fighter 2 definitely got me going back to the arcade.
Edited to add: look into the MiSTer FPGA project. I've had one for 5 or 6 years and it scratches an itch where most emulation falls short.