What HDD to choose?

I’ve got a Macbook Pro 13" with (unfortunately) a 320GB 5400rpm HDD:( which is pretty slow. I want to get a new HDD or SSD. What to choose? I’m in doubt whether to get a HDD or SSD. I want a lot of storage and a fast system. With a HDD you get a lot of storage, but with SSD you get a fast system. Or should I get a hybrid disk to get the best of two worlds? What do you guys think?