Sandwich cookies here tend to be smaller because it's two cookies, so each cookie is half the size. I'll comment that homemade cookie looks a bit on the large side to me.
For me, the "perfect" cookie size is that of a Hob Nob. Not too small, not to big, it's just right.
Favorite store-bought cookies...I'm pretty easy - I like vanilla sandwich cookies. Favorite common homemade cookie would be an oatmeal-raisin cookie or a sugar cookie.
I worked at a cookie factory for about two months - the kind of place that made cookies for other companies that used cookies (like when the ice cream makers sell ice cream cookie sandwiches, they used our cookies). They also made cookies for institutions (prisons, schools, senior homes).
My job was to manually enter all their cookie recipes into a new computer system. The interesting part was that every recipe was scaled to make exactly one cookie, so they could easily compute any number of cookies. A typical recipe would look like:
.1286 grams sugar
.0177 grams raisins
Also, I learned that some cookies for senior homes and hospitals were made specially for people who don't produce as much saliva as younger people, because our saliva production drops as we age, and lower salvia amounts makes it harder to break down and chew regular cookies.
One benefit of working there - literally all the cookies I could eat, free of charge. They had a little outlet shop that sold seconds of baked and pre-formed frozen cookies, and there were always plates of fresh-baked cookies out, and I could eat as many as I wanted, and take home whatever I wanted. When I left on my last day, they loaded my car down with trays and trays of frozen cookies and bags and bags of baked cookies.
They also had so many flavors and combinations - things I'd never dreamed of. My all-time favorite cookie was one from there: oatmeal with rice crispies, dried cranberries, and white chocolate bits. Simply divine.