I initially bought a an M&Pc back in 2010 and had this as my carry gun for about a year until the Shield came out and I could get a hold of one. I liked the M&Pc, but the slimmer profile of the Shield appealed to me as a strict concealed carry gun, so I sold my M&Pc to a friend of mine and only carried the Shield. Over the next few years I continued carrying the Shield, but I missed the M&Pc as the Shield didn't fit my large hands as well and didn't have as much capacity as the M&Pc. About a month or so ago my buddy decided to get a Glock 43 and sold my old M&Pc back to me so I now have that AND my Shield. To be perfectly honest, I know it's a lame answer, but get both. I'll carry the M&Pc when I"m wearing jeans and at least a polo shirt, and the Shield when I'm in shorts and/or a t-shirt.
One thing I will say though since you are a bigger guy is to hold both of them. If you have big hands, it can be tricky getting a proper hold on the Shield with the slim single stack sized grip. It took me a lot of practice to get used to it since I have big hands.