Comfort is in eye of the glove holder.... Go somewhere with a big selection and try on as many as you can. 11.25 to 11.5 is typical range for MIF and 11.5 to 11.75 is typical range for 3B. 11.5 would be a good place to start for someone who plays both but there are some larger MIF players who use an 11.75, Correa is one example. Maybe have him try a Correa model A2000.
https://www.whatproswear.com/b...correa-wilson-glove/
https://www.wilson.com/en-us/e...seball/carlos-correa