I'm nit judging, just sayin'.... For what its worth a while ago it seemed playing on an LCD was blasphemy, noe there are some who will admit they actually prefer the LCD. I personally like lcds better...
There have been a lot of advancements. When lcds first came out, mame didn't handle them well, the colors were washed out... they were pretty much worthless except in their native resolution, ect...
Now mame has some dot-pitch filters that when combined with a high resolution output almost nail the look and natural blending of an arcade monitor perfectly. This does NOT lower the resolution btw, nor does it blur pixels together like the old "Eagle" blending options back in the day. It simply removes the blockiness in a natural pattern. Scanlines don't do this... they actually reduce the resolution by turning off every other line. Thus why I said you use a dot pitch filter and not scanlines.
I currently have a similar crisis to deal with. My aging, original mame cab has a s-video tv in it. The thing is going out. If I can't find a 25-27 inch tv with at least component out for a 480p, non-blurry image I'll have the option of putting another crappy svideo tv in there for 200 bucks, buying a 27 inch multi-sync for 5-600 bucks, buying an 8-liner for a hundred only to end up with a cruddy standard-res monitor that won't run vector games well or spend around 200 bucks for a 27 inch flat-panel that will look great, work with my pc without fiddling, but leave huge gaps in the top and bottom of my cabinet.
So basically my options are to throw a decent amount of money in to simply restore the cruddy image quality I already have, spend more money than the cabinet is really worth on a multisync, go on a snipe hunt to find a 27inch crt with component or vga in, or put in a cheap, nice-looking lcd and deal with the annoyance of a 16:9 aspect ratio. Damn I wish they made huge computer lcds in 4:3 that didn't cost a fortune.