1. When do you want your pounds -- weaning, as stockers, or are you feeding them out?
2. What are your genetics in your cows and what is your pasture environment -- how much genetic potential in the calves do your cows have the ability to realize? You can breed them to hot rod growth genetics, but if the cows don't have it in them to produce, then it is unrealized potential.
3. Again what are the genetics of your cows -- hybrid vigor can come into play, but if your cows are crossbred mutts, then a purebred sire will probably be best.
4. I appreciate all breeds, but raise and am partial to Angus. There is enough variety in the breed that you can find an appropriate sire for your situation in 1, 2 and 3 above.