Besides being easier to pick, prune and spray, you can plant two or more dwarf trees in the same space as your one standard tree. Al

Those pole fruit pickers pull down on the apples and frequently break off the spurs.

Well, it depends on a lot of factors. There are pro's and con's to planting dwarf trees, or to planting standards, or semi-dwarf, just like everything in life, I guess.

I've planted "min-dwarf" trees from Raintree that mature at 6 to 8 feet along the perimeter of my main vegetable garden. This allowed me to cram in a lot of varieties, yet still not shade out the garden itself. They are underplanted/planted between with various low fruiting shrubs, gooseberries, currants, Joy bush cherry, blue honeysuckle. The oldest ones are maturing now, and yield between one and two bushels. Those are the pro's. The con is that they are definitely weakly rooted, I have had to permanently stake them, because several of them have wobbled and started to fall over during wet, windy periods. I kind of question the longevity, too, I suspect they won't be around for 100 years like a standard could be, but then again, I probably won't be, either.

Our St. Croix County Extension here in Wisconsin does not recommend dwarf trees, as they are less hardy then the semi-dwarf or standard. Northwoodswis

Time to fruiting is another advantage. The smaller the tree, the sooner it will fruit after planting (and the sooner it will stop fruiting, but that is decades down the road). If you bag, you have to reach with your hands the top of the tree.

No fun pruning full-sized trees, and the older you get the less you like being very high up on a ladder. Same with thinning the fruit or even spraying, which will almost certainly become necessary.

12 feet is plenty high for a fruit tree, to my way of thinking, and 15 feet is too high. Lots of people keep their trees short enough to do almost everything from the ground.

It's easier to maintain fruit quality with a lower tree. You can keep the center properly thinned out and manage the branches better when you can get to them easily. And pickers and pole pruners are unwieldy and imprecise. I hate trying to use them.

We prefer semi standard trees they produce a lot more fruit than a true dwarf. We keep them pruned so the ladder work is minimal
Another option if you must have multiple varieties and only have a small space is to get a multi grafted tree. Dwarfs are very shallow rooted wich can be bad in a drought year. They are much shorter lived too.
Id go with semis they are easy to keep low and they have nice root systems to support a tree. It really depends upon your space. We don't use dwarfs cause the tree takes much longer to grow and fully come into bearing crops.
Happy growing
Cory the son of a fruit freak

True dwarf apple trees, planted in sandy soil in a windy area, often will require staking for support, for the whole life of the tree. In California where summer rain is rare, regular irrigation will also be required. Al

Yes...only plant if you have allot of moisture, don't expect long life and don't want to climb a ladder.
I like growing them high, ladders have become allot safer, have seen one my brother uses in Switzerland,.. got two wheels, easy to move, similar you see in some of the big box stores when the girls get that item high up on a shelf.

Coconut head, you should tell us where you live because the value of apple dwarfs is affected by location.

Dwarfs can't grow above the browse line of deer and so must be permanently fenced in some way if they are an issue, they are less drought resistant and need to be irrigated. Most dwarf rootstocks are susceptible to fireblight and are much more likely to be killed by it. You can't baffle away squirrels or racoons because you need at least 4' of trunk before first branches to do this.

Dwarfs are also more attractive to voles (field mice and under ground mice called pine voles) and more subject to fatal girdling by them during winter.

However, all over the world dwarfs are taking over or already have taken over in commercial apple orchards. They require much less pruning and that pruning requires less skill. Because they stay open to the sun, dwarf fruit tends to be better colored and generally of higher quality. As said here already, they crop a couple years sooner as well.

A nice compromise if you live in an area without too much fireblight is M26 which is a semi-dwarf that at maturity can often be self-standing, depending on soil and other factors of site as well as cultivar.

Vigorous varieties on 26 can even be grown tall enough to be above the browse line with scaffolds above 4' of trunk. They can also be kept at a height where step ladders are not necessary- depending on how you train them.