First, directive pruning can deal with the effects on the fence, so that can be controlled. 5 feet is pretty darn close.
My bible for crabapples is the J. Frank Schmidt nursery crabapple info chart. Granted, they express their research in Oregon, far from most of the rest of us.
Prairifire, according to their research, has excellent resistance to scab, rust and mildew. It has good resistance to fireblight.
However, here in my area, I have observed a lot of canker disease in this particular crabapple. You might try a mixture of others. Mono-planting can be really pretty or really problematic if a particular blight descends upon the variety.
Please realize that I am a "diversity" planter and feel that all of one species or variety can be either good or possibly disasterous. Just my way of thinking about what we plant...
hortster

suz, my small prairie fire looks EXCELLENT this year and is relatively limbed up.

IMHO even though I recommend the prairie fire I say go with variety and even all Crabs seem a little close genetically for me.

I would vote for

-dogwood (Cornus Florida or Cornus kousa) depending on your feelings of native vs disease resistance.

-redbud (Cercis canadensis). Not quite the fall color but there are now a couple varieties on the market.

-serviceberry has my interest new as well. I just purchased a "tree" form. We'll see, but I love the bushes.

-Cornus Controversa, Giant Dogwood, also has a spot in my yard. It seems to want to spread wider buy mine is preparing to flower at just 3 years in the ground (and I plant SMALL!). Fall color is OK but not dogwood great like I am used to.

crabs will get to about a 20 foot canopy .. will your neighbors care .... if your tree.. 5 feet from the fence .. overhangs about 10 feet .. and drop leaves and stuff on their lot???

ken