In my world they are different knives for different applications. In the week, in an office environment, a mini-grip works better for me. It is smaller and more discrete but can handle the cutting I do in that environment (opening boxes, cutting off the hard plastic tape, peeling an apple, opening packages, etc.) - does a great job without traumatizing co-workers too much.
Weekends I carry a larger knife, I like to spend time outdoors so a large Grip works better around a BBQ, trimming branches in my garden and a bit of food prep - nothing that the mini can't do but the large Grip is just more fun.
I agree with the comments on the large not being as balanced as the small and the sound it makes when closing sounds "plasticy" but I can (and do) overlook that because the handle fits my hands so well and it is such a comfortable knife to use (both sizes).
If I had to choose one, I'd go with the mini as I spend more time in an office than outdoors. Having said that, while other, more expensive, knives have pushed mini-Grips out of my "office" rotation, the large Grip fights well above it's weight in the weekend folder rotation stealing pocket time from Sebenzas and the like because of the handle ergos.
Personally, I prefer the Ritter blade on both and of course Wilkins or Cuscadi scales take the Grips to a whole new level (and price point if you are comparing to other alternatives).