To me buying cows or heifers either one at a regular sale is a roll of the dice, but I'm am doing it currently as well. I'm also not convinced that buying off a farm is always problem free either. I will say that in my opinion heifers stand a better chance of turning out well over a cow. The cows are usually there for a reason. It's true, a lot of folks keep their best heifers, but still can get some pretty good ones, if careful. I have bought several cows and heifers through the ring this year, 2 with calves and the others bred. One I should have not bought, I resold, the others that have had calves are doing well.
We have gone a different route than most, in that we prefer Hereford, and I have a hard time letting a well behaved cow or heifer with some "ear" get by, so we have a few of them. Have had far less disposition issues with the Herefords and even the ear crosses than anything else, I try to watch very carefully while they are coming in as well as how they act in the ring.
It just depends on what happens to be at the sale on a given day, we got a hold of several nice Angus type heifers in 500 weight groups last fall, they are now bred, 2 were bred young before we bought them, and have calved and are doing fine with their calves.