The best place these days is probably the Qmtech clones from Aliexpress.
Taki Udon also makes a very well received unit called the SuperStation that has analogue outputs. The worst part about the SuperStation is it doesn't support Snac adaptors out of the box, so you need to get the dock to use an authentic controller for anything other than PS1.
There are actually also very good clones on the market of both SNES and Genesis made by companies like Hyperkin and Retrobit which do a reasonably good job of recreating the original hardware and can be hooked up to a CRT or modern TV. When paired with a flash cart, you can get a pretty authentic experience on the cheap. Stay far away from the NES clones, though. The modern clone chips they use don't faithfully recreate the NES' sound.
I think the M64 coming out this summer will also be a good option. It's open source, so it's only a matter of time before the Mister cores are ported. It seems there are some kinks with the N64 core, but I think they'll have them worked out fairly close to release. The owner is pretty committed to the product line.
Analogue also makes a handheld product called the Analogue Pocket which has some FPGA cores. It apparently does 8 & 16-bit + GBA pretty well, but anything more powerful than that like PS1 or N64 is either spotty or a no go. Like all Analogue products, they do the whole artificial scarcity thing, so it can be hard to get your hands on one. It's not as good as a Mister, but in terms of an all in one handheld FPGA solution, it's probably the best one.
There's also a stripped down operating system for Raspberry Pi called Replay OS which amazingly has managed to come close to an FPGA in terms of input latency, with only a frame of delay.
There are also many boutique FPGA products that do a single system very well like the Analogue 3D and the Modretro Chromatic, but I wouldn't recommend any of these unless you already have a cart collection you want to play.
*Edit*
I almost forget. Don't forget to consider the humble New 3DS. A hacked 3DS plays GBA - 3DS natively, that includes ports of many of the best first party SNES and N64 games as well as many RPGs from the SNES and PS1 era. There are some homebrew ports like a native SM64 port that runs at 60fps. There are native ports of a bunch of Sega games. Once hacked, the 3DS has a beast of a library of games it can play natively. It also emulates GB/GBC and NES pretty well, but once you get into later systems, things are touch and go.
My point here is unless you owned the older systems back in the day, you're never going to have a truly authentic experience with them anyway and the idea you can is an absolute fucking grift. There are many options today that offer a way to run a lot of these old games without the tradeoffs traditionally associated with emulation.
