If you're really serious about emulation then springing for a specialized machine is the way to go. I've got an RG353M as my primary system and a Funkey S as sort of a novelty.
The RG is exactly what I was hoping for. It has a 480p 4:3 screen that makes everything look exactly like you want it to. It runs off of retroarch so you have all the options you want for filters, but I find that the basic bilinear option gives me exactly what I'm looking for on that screen.
The system itself is solidly built with a bit of heft. The M model comes in a metal housing that looks and feels great. The buttons have a solid push to them, like a deeper set DS Lite button set up. I've only played SNES and PS1 games on it so far but have had zero problems of any kind with them.
So far I've been milling through Square's SNES library, and in the two months I've had it I've played it more than anything else I've owned all year. So far I've beaten FF2 and 3, Chrono Trigger, Secret of Mana, Link to the Past, Symphony of the Night and RE1 Director's Cut, and now I'm playing Mario RPG and FF7. I'm just pleased as punch with this thing, I can see it being my main gaming device for quite some time.