Mesa themselves recommended the Presonus EQ3B. They said it came closest to the factory sound.
I use a MXR 6-band as it is quiet and toneful, but it only goes up to 3.2k, and doesn't hit the 6.6K band the factory EQ does. The MXR 10-band version has higher bands at 4 and 8. Too out of place for Mark tones, IMHO.
The Boss GE-7 does have the 6.4k band, but I find it to be a noisy and thin sounding EQ.
I have a vintage Furman reverb with a built in PQ3 section that has that same smooth sound. Always a good choice if softer bottom end, scooped mids and full highs are what you are after. It sounds the least like the stock Mesa sound but the bands are not notched, they are passed.