Since you are interested in using a VGA monitor, and show interest in playing older arcade titles, is there any particular reason you don't want to use a MAME PC?
Consider this: Mame has the real arcade versions of most titles, and there are other emulators that support the games Mame doesn't have.
Scanline support is typically built in to emulators and it can output to a VGA monitor directly, with no hacking, or a PC can also be made to interface with a arcade monitor very easily with the proper drivers, and a JPAC will allow you to interface it directly with any Jamma cabinet.
If you aren't using a Jamma cab, a IPAC is also available that works great too.
Not saying you can't go with an old console to get games running, but it isn't the easiest thing to get going, I originally threw a Sega Saturn into a cab many years ago when I was just starting out, and I was pretty unhappy with it pretty quickly as home ports are usually inferior to the real arcade games, not to mention sticking my hand into a cab to swap discs hurt my arms pretty bad after a while.
Not trying to be a jerk or anything I'm just curious.
Hah it's ok. I guess I don't want to have too much emulation. It may not be entirely rational but I like the idea of a game running on actual hardware. As far as home ports being close to the arcade no home consoles comes closer then on the Dreamcast. It even had a special function where if you used 2d, you could turn the 128 bit cpu functionally into two 64-bit cpu's to both read and write.
That and I'm also a big Dreamcast fanboy ;).
As far as arcade accuracy with older games, They come as close as any platform. I dpn't see any significant difference oin the neo geo ports either. This discussion explains a lot
http://www.neo-geo.com/forums/showthread.php?117207-Need-arcade-perfect-ports-for-Dreamcast.
So you have the naomi ports, which only might have less high resolution textures and some of the better ports of older 2d games. In order to get true scanlines a CRT VGA monitor would work fines with the hanzo VGA box which has the option of half scanlines/scanline wthickness. Since you get some scanlines on a 31k hz vga monitor, but you need half of one added for the higher resolution to get as close to true scanlines without buying an expensive actual arcade monitor.
https://www.youtube.com/watch?v=XiCsiZFs6DE (a very bad game to use a scanline generator on, older pixel games are much better to show the difference).