If you want something bigger than your peruvian then it would have to be a female yellow annie. Males get around 6-8 feet. I was looking at getting a yellow annie but I was looking for something that is calm most of the time. If you get a yellow annie make sure you get a CBB hatchling. Mistreated annies can become the spawns of satan and same with WC individuals. Also ive heard that they have a weird way or striking. It most like lashing, the strike side to side and can leave a nasty mark.

On the other hand with the burm, if i was to choose, i would deffinetly choose the burm. I love the look of the normals burms and some of the morphs are amazing. A burm will get much larger than your peruvian. Im going to be getting a half dwarf burm soon and i can't wait. I always wanted a burm, but couldnt deal with a 12+ foot individual.