The MX808S is one I've been looking at. It
looks like it does a fairly wide range of things. It doesn't look like it can do any programming, but otherwise looks impressive for the price. It's definitely on the list of ones I'm considering, so positive to hear from someone that's had a positive experience with Autel.
I don't really know the differences between all the models. Mine is a MP808 Pro, which I don't believe they make anymore and may have been transitioned to one of the "9" series. They do have alot of 808 versions available at different price points.
As far as ECU coding goes the only thing I know for sure about the MP808 Pro is I was able to code a used brake module with "As built" data on my F150 so the MP808 Pro supports at least a limited amount of coding. I've also seen videos where it unlocks "hidden" features on certain BMWs but I haven't used mine for that.
It has a surprising amount of capabilities though for sure, esp at the price I paid for it. Some of the projects it's handled (aside from routine reading/erasing codes):
Mercedes E350 - put braking module into service mode so I could replace pressure accumulator; replaced/reset six airbags and three seat belts that were set off by failed driveshaft (non-collision); reset adaptations after engine rebuild; deactivated legacy modules that are no longer supported by manufacturer (roadside assistance, etc); diagnosed electronic transmission issues and other sophisticated engine systems (intake manifold variable timing, etc).
BMW 328iX - diagnosed many engine issues and electronic sensors only one that it didn't handle 100% was a failed variable timing solenoid that was actually replaced with a new one that was also bad and lead me down an expensive rabbit hole ... needed to buy a scope and some assistance from this board to finally confirm issue and nail it down.
Ford F150 - brake module (recoding), EVAP issues (fuel tank venting solenoid), MAF sensor, COP misfires, etc.
Chrysler 300 - transmission solenoids and coding new Transmission control module to vehicle (basically just coding VIN to new module).
Note the only vehicle I had a problem with was a late model Honda - it would not connect to car. I forget model and year but it was within a few years ago. Worked fine on buddy's older (2015ish) Honda though.
Anyway, good luck.