Have to say that with soup it is all about the stock. You don't need a huge pot. Just one big enough for your needs. Mine was a tenner from tesco and holds a chicken carcass plus all the other stuff and I think about four litres of water.
Favorite soup is spiced butternut squash. Cook squash in veg stock, blitz it all up, add some creme fraiche and whatever curry paste you prefer, we like tandori, blitz again return to heat. Yumster!