I totally agree with what greyphase said.
The thing about heritage apples that you have to remember is that there are many of them that have been propagated for a purpose, and that purpose may not suit your needs. I have good ones and bad ones, and after seeing how devastating fireblight is in my area, resistance to it is more important to me than anything else.
For instance, I have one tree (American Summer Pearmain) that has been in the ground 9 years now, and I'm yet to eat the first apple off of the tree. In this time there has been one year when FB didn't appear, and the tree had a fairly decent crop of apples. When they were about a week from being ready to pick, I sprayed them one Friday to keep the pests away until I harvested them. The next day (Saturday) a big bunch of Jap Beetles came to the tree and ruined ever single apple. The spray the day before didn't phase them. The variety had nothing to do with the apples getting destroyed, but it had everything to do with one crop in 9 years.
I had another variety that was worse than it. I ate one apple off the tree in 8 years, and last year I just got rid of it. However, other heritage varieties planted at the same time as those two have given me great crops for several years. The best I can tell from my research, that apple I got rid of was propagated because it was big and red and showy. But, if you don't get to eat any of them, that isn't much consolation...LOL. I love buying from Big Horse, but honestly they have some varieties I wouldn't plant (now) if they gave them to me.... But, they have some great varieties as well.
So for me, I look at disease resistance first and foremost now. I might be willing to do a little spraying (very little) at home, but on my apples 20 minutes away at the farm, I won't be spraying much if any. I will do some spring maintenance, but otherwise they need to be able to make it on their own. It looks like I have a bumper crop on several this year (first cropping) so we will soon see what makes the grade.
However, this may be another of those unusual years without FB. It hasn't shown up yet, and I think its time. So I may have to wait another year to see which ones really make the cut.