Go with the 20" - I did for my ML350.
Bigger is always better

stas2007, I'm nearing the time for replacing the OEM on my 2013 550. I have the 20 inch AMG which are 9 inch, I believe. The 295 would be nice, but are considered to be "pushing the limit" on 9 ich rims. Is this the setup you are using? Or, are you running 10 inch rims? And, do you have the air suspension? Thanks.

I got the 20" AMG rims and AIRMATIC as well.

In the last photo, looks like 20x10 AMG rims from the W164 ML63. I had those on my W164 for a while. I ended up taking them off because the extra weight was detrimental to handling on that vehicle (2006 ML350 Airmatic).

Any one had rep 20 on their ML? I know a seller on the forum, but could not recall his name.

I HAVE A 2014 ML350 BLUETEC COMING INN AT THE END OF NOVEMBER.
IM TRING TO DECIDE IF I WANT TO PUT 20'S, 21'S OR 22'S ( RIMS ) ON THE VECHICAL WITH WIDER TIRES 285/35 TIRES.
I WAS THINKING ABOUT THE 22'S BUT.... I WANT TO STILL KEEP A VERY VERY GOOD RIDE AS I FELT WHEN I TEST DROVE A ML350 BEFORE ORDERING ONE. I WOULD LIKE A WIDER TIRES BUT NOT NO THIN TIRES OR LOW PROFILE TIRES. I WANT SOME THICKNESS ON THE TIRES FOR A GOOD COMFORT LUXURY RIDE.
CAN I GET SOME ADVICE TO SEE WHAT RIM SIZE LOOKS BEST AND STILL GIVES A GREAT LUXURY RIDE OF COMFORT. AS WELL AS OPION ON THE WIDTH (WIDENESS OF TIRE ). I NEED SOME HELP.

If ride comfort is important, I would not go above 20s. Airmatic helps, but larger sizes will definitely compromise the ride. Even the ML63 comes stock with 265 width, which is fine for all around performance. If you want a wider look you can go 285 or 295 with the proper tires, but be aware that the extra weight is detrimental to overall performance and handling.