Hubbards are great, delicious and hardy but not the fastest growers. They're ready in 12-14 weeks. I believe Ross are faster (8 weeks apparetly) but not as tough.
Day olds are easy to get and takes the hassle out of hatching.
They all eat like something possessed. I used to have figures from when I had Hubbards but I'm afraid I've lost them but suffice to say, don't let them feed ad lib!!