I don't really go to Subway, but I do work at a Publix deli and if I want to get lunch I usually go for...
Roast beef on multigrain bread, with mayo and lots of the pepperhouse sauce. The cheese is 3-pepper colby jack if available, pepperjack if not. Toasting is optional (I usually go for it if I'm on break and can eat it immediately, otherwise it gets soggy). Toppings are very light lettuce, tomato, plenty of garlic pickles, cucumbers, and olives. Then one more drizzle of the pepperhouse on top, the deli dressing, and maybe some salt and pepper. It is... very, very greasy, but it's absolutely delicious.