Xbox 360 to Xbox 360S was brilliant. - Smaller, quieter, better cooling, built in-wifi, couple extra USB ports, HDMI port. (Original Core didn't have HDMI)
Xbox 360S to Xbox 360E. - Garbage. - Lost Multi-AV port, Optical Audio port, Lost a USB port.

Best (in no particular order):

PS2 slim
PS One
DS Lite
Gameboy Advance SP
Switch OLED (such a great screen)
Xbox One S

Worst:
Genesis model 3
PSP Go
PS3 super slim
Gameboy Micro (yeah it's cute, but smaller screen AND removed backwards compatibility? Why?)
Wii mini
PC Engine Shuttle (and, honestly, all of the TurboGrafx revisions kinda suck to some degree because of the sacrifices to functionality)

Worst is PS3 Slim. It lost the card reader, lost BC, lost otherOS. The launch model was so much better except for ylod.
Best X360S, HDMI out added and didn't kill itself anymore after a couple months use lol.

BC was removed well before the Slim model. I want to say it was the 80GB model that removed it.

Anybody remember the small genesis and sega cd combo? That was pretty amazing.

Edit

Apparently I should have kept my CDx, the thing has some value.  I don't even know what I did with mine.

I remember the third PS3 looked really cheap and bad. Also PSP Go for $249, what the hell were they thinking?

True, and otherOS was patched out well before as well. I had an 80GB model as well since I had bought a 2nd one as blu-ray player for my projector as it was still cheaper than a standalone blu-ray player at the time. Both eventually died of ylod :( And then the slim didn't have the card reader anymore either.
At least the slim is still kicking, never needed to buy the awful super slim.

Most of the PlayStation slim consoles are pretty great. I've owned ps2/3/4 slim models, will unfortunately break that streak with the absolute garbage that is ps5 slim model. Ds lite might be my favorite, improves on pretty much everything compared to the original ds

Super Slim is great and very reliable. Still works like a charm.Plus I prefer top loader less parts to go wrong

Best:

1. DS Lite
2. GBASP
3. PSOne

Worst:

1. Genesis Model 3
2. Wii Mini
3. PS3 Super Slim