We have all of them, but the worst by far are the deerflies. Foruntately we don't have the clouds of blackflies where we live like they do in Northern Ontario, and even the mosquitoes are tolerable, but the deerflies make life hell for horses, cattle and black dogs, and people. If you aren't moving, they aren't bad but as soon as you go for a walk, they attack. The only solution is to stay deep in the woods. Repellants aren't very effective, the only thing I've tried that seems to work (for a short time, it doesn't stop them from flying around your head but they don't land) is a mixture of essential oils that I've put together. Those stickers that you put on the back of your hat will catch some of them .
Some areas of the country are intolerable because of the biting flies- blackflies, mosquitoes, deerflies, horseflies- depending on where you live. There's even a folk song that's been written about blackflies in Ontario: https://www.youtube.com/watch?v=nUZYuWfg7NA
They don't seem to bother the chickens, the blackflies and mosquitoes will bite the chicken's combs though. I have put mosquito screening in my coop, I'm sure being harassed by biting flies will lower egg production.
Blasted deerflies ruin every summer, they come out at the end of May, peak in July and are thankfully mostly gone by the end of August. Fall is the most productive time of year for me, last year was fabulous, we had a very long warm fall and a short winter.