If I am doing a cold sub, I will typically go with thinly shaved ham & turkey, but it's gotta be the ones that aren't processed so much that they have the texture of bologna. Our local deli sells a "turkey off the bone" lunch meat which I love, since it's not all ground up and formed into a loaf like the cheaper cuts of lunch meat are. They also sell a lunch meat ham they prepare in a similar way, only they roast the ham in store, and thinly slice it so it melts in your mouth. For toppings I am relatively traditional - lettuce, red onions, tomatoes and pickles, with either a little bit of mayo or some red wine vinegar and olive oil.
If I am in the mood to splurge I will go with all Italian cold cuts, some of which are usually more expensive, such as prosciutto, along with more expensive Italian cheeses. I will also include things like roasted hot peppers preserved in oil, perhaps dress the roll with some pesto too.
Sadly many of the Quiznos closed in my area, but I used to love their Monterrey Turkey sub, which had turkey, bacon, Monterrey jack cheese and a red pepper sauce on it. Even after they took it off the menu, they would still make it for me when I requested it.