What is the best way/report to show which program made a lead MQL?

It depends a lot on your system. What causes someone to be MQL in your Marketo instance?

So this is why we're having issues:  

1. There's the initial program status change or interaction tracking which happens in a program (this is what we are looking for).
2. From there we have a "Lead Scoring" Program which changes the score based on the interaction or program status change (this program is operational/ in an optional channel) 
3. Once a lead hits a certain threshold of points, it is pushed to MQL status in another operational program (also operational channel). 

Hmm. Tricky.

You might be able to put in something that is a trigger campaign on high scores inside the program that records the program name to a custom lead field.

You may be able to run this as a {{lead.Last Intersting Moment Desc}} at the time you run the MQL flow. That will require you to have some IMs based on various Program success statuses.

You can also populate a Last Touch field that each program populates when it runs...probably at a Success Status flow if that's what you're looking at.

If Fills Out Form...then Program Status=Success and Last Touch=PROGRAM NAME

then you have a central flow that runs the MQL and says

MQL Cause = {{lead.Last Touch}}

to ensure that note is permanent. 

@Josh - I like it - but I don't think Last Touch = Program is possible without entering program name in every single program. I think it can only be Last Touch = Campaign Name? I believe the system triggers can only do campaign name not just the program. 

Building off of what Josh suggested, we include the following three flow steps in the smart campaigns where program success is acheived - in this example, it's the smart campaign when someone fills out a form to download content on our website.  Every one of our programs includes a local token ("Program Name") to make deployment of these flow steps easier: