If by any means possible buy organic ones and eat them WITH the skin.
The skin of a pear is very important and comtains -on top of a lot of fiber also much more nutients than you find in  the white [flesh] of the pear
Apples and pears are very good food for diabetes patients and it is such a pity that dieticiasns still "discourage" diabetes patients to eat plenty fruits!
Also the ckolesterol decreasing efect is of great nenefit [just like bananas and pineapple-ananas] by the binding of the fibers of the pear with bile-acid which also help reducing the risk of colon caner.
Fruit are of immense importance for reducing the risks of gastro intestinal cancers. In the past I wrore you about strawberries and oesophagal cancer!!

Pears are also probably the best fruit which is good to give babies when they can start eating fruits.
If people have a high allergy temdency. pears are in general not excluded from the diet.....thye are hypo-allergenic.
There are so many varieties of pears I can't tell you what variety is the best to buy, but if you can get red-skinned organic pears them choose these.