Clone consoles never have a good sound chip in them, and often aren't compatible with the older TVs that the original systems were meant to run on. Old tube style televisions didn't have as crisp pixels as modern TVs do. This created a slight blurring effect that a lot of older game makers relied on. Also older tube TVs didn't draw the entire image all at once. They drew it line by line millisecond by millisecond. If you were to take a picture of one of these older tube TVs with an ultra high speed camera you'd only see on line of pixels in the resulting image. This also has a slight effect on the way the game looks.

Oh yeah, second model Genesis didn't have a sound chip as good as the original. So you need the big OG Genesis/Megadrive if you want to experience the games as they were.

TL/DR: You need an original piece of hardware, and a tube T.V. from at least the early 2000's to get the original experience.

Some of the 1 chip options are really terrible but there is some great clone systems out there from 3rd party makers.

Basically anytime you see Sega and ATgames on a product run the other way from it, unless you're deaf... and maybe blind, then you won't notice the difference, but honestly for me while I have almost all the OG hardware back to my Atari 800 I just find it so much easier to sit back at my projector with the PC connected to it and enjoy libraries of games from all those systems without having to go digging about for my cables and convertors to get what is pretty much the exact same if not better experience from an emulator.

The AVS I reviewed last Christmas does a near-perfect (exceptions always) hardware simulation of the NEW via FPGA - no software emulation required. The NT and Super NT are similar. 

I would say that excellent clone consoles are available, it's just whether you think it's worth the effort when - as you said - the games CAN be played via emulators if you don't mind the gray legality and occasional compatibility issues. 

I pefer an emulator on PC.

Just listened to the Super NT's soundchip, and holy cow! Damn that's even better than the original. So crisp! I might have to shell out for a Super NT eventually. $189 is a bit pricey, but you can't deny the quality. Now, I wonder if the it's compatible with older TVs. I really don't like what newer TVs do to older games. 

P.S. An original model SNES will cost you $50 - $70, and an original model Genesis goes for $40 - $60. Top loading NES goes for $100 - $120. 

A new contender has entered the ring, and this one's a good one:

I'm cool with it. Somebody has to keep the retro stuff alive when the original isn't there anymore.

Absolutely yay. Especially since we have a whole new world opening up in terms of emulation with FPGA solutions coming out to the market more and more. Sky is the limit. What I would really want is an N64 FPGA based console that fixes all the dreaded problems people had with playing N64 on their modern TV's. Definitely something to fix that hardware driven anti aliasing filter.

There was the Sears Telegames that was a license clone of the Atari 2600 so...

And, no, I did not go to your YouTube page. 

Oh, there was also the Coleco Gemini:

They need to come with either a cartridge slot/disc tray to play the original games, or come with an array of pre-installed games, or both. Playing pirated ROMs are a no-go for me, so there needs to be a legal way to play them.