Horns are a recessive gene. Angus are suppose to be polled which is a dominant gene. So if you breed your cow to a horned bull, it should have polled calves. If you breed your polled bull to your angus cows and they are not homozygous polled, you can get horns if the bull has horned blood.
Since we have horned herefords, I have heard a whole bunch on the subject of horned versus polled. Horned bulls aren't suppose to fight as hard as polled bulls because they get their horns sore and stay away from each other. It is also said that horned bulls will not "buddy up". Polled bulls you shouldn't have to dehorn, but if you tag your calves when they are born, you can use dehorning paste and the horns are history.
The most important thing is that you get the best individual you can find for the money that you have to spend. Also, it is important to get a bull that has been vaccinated for the diseases that you have in your area. It also depends on what kind of country you are going to run them in. You really don't want to turn a bull that has been highly fed out on tough country, the "hot house flowers" will soon fade. Reputation is everything.
Ask to look at the cowherd. That is most important of all, especially if you are going to keep your heifers. Herefords are known as a "maternal breed" so if you are going to sell all your heifers, you might want to get a bull of a "terminal breed". EPD's are worth looking at, but like I was told a long time ago, "EPD's won't help you sell a good bull, but bad EPD's can help you not sell a good bull". EPD's rely on information turned in, some families do not have much information and they are perfectly good cattle, they just don't have high numbers.
Temperment is very important also. There are different families that are known for being more docile than others. There is no bull alive worth getting someone hurt over.
If you use horses, ask if the bulls have been worked horseback. It isn't fun to be faced off by a bull that has never seen a horse. That isn't a deal breaker for us but if go to a place and don't see any horses around and a bunch of ATVs, be careful.
It is kind of like asking if you should marry a blonde or brunette. Depends what they look like and what you are looking for. We still keep our horns on our cows and don't slope our bulls' horns! They are "Horned" Herefords, not bulls have horns and cows don't!! I know, we are inbred nitwits. We even still horn brand our cows and bulls, we ear tag but we don't know each one personally so we have them identified.
Too bad is isn't the 1940's, I would have a great resume~ I know how to horn weight right, can read horn irons from the back, can fix a sickle mower, just a whole lot of things that most people don't do anymore!LOL!