Stark Brothers have always had good quality trees. Millers was one of my other best choices; they recently joined with Stark Brothers, and their trees are in the Stark catalog now. Fall planting in suitable zones gives the root systems a good head start.
Renais

Hi! I order all of my trees on line. These are my favorite sellers

1. Arboreum. Their trees are more expensive but you receive a very well rooted tree, impeccably packaged. Their selection of fruit trees are more obscure than most sellers. That is what makes them special. I have ordered Peaches and apples.

2. Raintree Nurseries. Some have had problems with Raintree, I never have. They have sent me quality trees. Only once did a tree die, and it was replaced by a far larger tree the following spring. I have ordered apples, plums, pears, and apricots.

3. One Green World. Also excellent. I have ordered apples from them.

4. Cummins Nursery: I have ordered apple trees from them as well.

Most of my berries (strawberries, currants, blackberries and raspberries, are from Norse Farms. Excellent product and service!

My top 3 for trees:
ACN
Cummins
Grandpas

You can check out Cummins and ACN now, but Grandpas won't be updated for a week or two.

I agree with MrsG that Nourse is great for berries, especially raspberries and blackberries. But for some types of berries I would say RollingRiver (bush berries, like Gooseberry/Currant/Elderberry/etc). DoubleA is the place for grape vines.

Some of the rarer or less well known varieties can be found at trees of antiquity. For info, they are out of Ca. so might not have trees adapted to the OPs area.

Here is a link that might be useful: http://www.treesofantiquity.com/

Stark Bro is good with the exception of not identifying the specific apple dwarf rootstock. My answer from them was M9 or M26.

All of the good ones I know of have been listed

Include Edible Landscaping if you are looking for good varieties for the mid-Atlantic areas.

Below is a thread that I started earlier this year. It has multiple reviews of many online retailers.

As an update to my review, my order from Burnt Ridge was excellent.

Here is a link that might be useful: 2014 Online Retailer Reviews

same here. Burnt Ridge and Raintree. One Green World is great, but it's so close it's ridiculous to mail order from here.
John S
PDX OR

Fedco Trees is a great source for quality cold-hardy stock. Apples, pears, plums, peaches, etc. Lots of interesting varieties of fruit, ornamentals and various other perennials. The catalog is just fun to read as well, lots of info and illustrations.

Another vote here for Raintree. I've ordered many varieties and they have generally grown quite well and been productive.

Another vote here for Raintree. I've ordered many varieties and they have generally grown quite well and been productive.

Most of the names I'd have mentioned have been, with the exception of St Lawrence Nursery. They are good for cold hardy trees and have a very good selection of apples. They are a small, family run place, and as such may take a while to get back to you in their busy season. But their trees have always done well for me (with one exception which they replaced).