Subway and Kotipizza.
Subway is quite affordable, especially if you have the mobile app and it doesn't feel that unhealthy. It's also really quick unless there is long line. And you can change the fillings, sauces and toppings a lot so its' not always the same product. I visit subway most often.
Kotipizza as you can guess from name is pizzeria chain here. Downside is that it's expensive compared to Turkish kebab-pizzerias, but their toppings especially bolognese one are great. You get quite wide arrange of toppings u can choose from as well. I don't go often there, since it's expensive, but it's good.
Oh and there is one newer chain, Firewok which makes asian stir fried noodles. Not cheapest either, but you get full meal with that one and it's really good.