My reaction when picking up my new shoes from the post office:
My pair of Altra Lone Peak 2.5 Trail Runners lasted just over 800 miles of hiking including the Wonderland Trail around Mount Rainier, numerous hikes near my home state of Maryland, and the first 634 miles of the AT. I liked these shoes so much after the Wonderland Trail that I bought a second pair knowing that I would be wearing out a couple of them hiking on the AT.
Shoe Repair
This repair held for another 150 miles, then the rip really just got out of hand when it rained for 5 days on my way to Pearisburg.
Hiker's feet start to spread out over time and even my extra wide Altra's couldn't handle my growing feet. After about 550 miles some tears began to form on the outside edges and I stitched them back together along the more durable rubber of the logo and the sole. I also globbed Shoe Goo over the stitches and on the fronts where the toe guard was starting to peel off. This held together for another 150 miles or so before I blew out the stitches when I was crossing some rocky terrain and my foot was at a sideways angle. Most of my weight was then against the side of the shoe instead of in the sole. I hoped that the gear repair tents at the Trail Days festival could stitch them back but they all said it was impossible...then I pointed out the remnants of the red thread and said "I did this on the trail. And aren't you a professional seamstress?" However, my tread was also wearing out and the expected life of trail runners is only around 600 so I put the call in to have my new pair shipped to the next town. You can see how worn down the tread is in the first photo.
Boots VS Trail Runners VS Sandals
I prefer trail runners because they dry out faster, are lighter, and give your toes more space. When long distance hiking your feet are going to get wet, I don't care how many layers of Gortex your boots have or how tall and waterproof your gaiters are, your feet will get wet. One friend had to stay behind in Gatlinburg for a few hours and attack his boots with a hairdryer because they didn't dry out over night.
Also with long distance hiking, weight is the enemy. Extra ounces on your tent, backpack, clothes, tools, stove, etc will add up to pounds (remember, Work = Force * Distance) so shaving weight wherever possible can only help you, especially on your feet. It is estimated that the weight of your shoes is equivalent to 5 times the weight on your back so having boots that weigh a pound more than shoes would be like carrying an extra 5 pounds in your pack.
Trail runners (especially Altra's with an extra wide toe box) tend to let your toes spread out more than boots which reduces the chances of blisters. Friction and moisture are the leading causes of blisters so if you can reduce friction by giving your toes more room then you're going in the right direction. In my opinion, the only advantages boots have are durability and ankle support which would've saved me quite a few rolled ankles. My trekking poles and cat-like reflexes allowed me to shift weight off of the rolling ankle so I've avoided injury but you can do ankle-strengthening exercises when sitting at your desk...or go hiking for hundreds of miles and they'll get there.
And for that last contender, sandals. Yes, some people hike in sandals. They argue that they're even lighter than trail runners and dry even faster which are both true but they also offer no protection. I would've broken every toe at least 10 times by now if I didn't have any sort of front guard on my footwear. To each their own but I firmly believe that trail runners are the best option.
Drying Out Your Feet
Even if it isn't raining, I always take my shoes off when I stop for lunch or any longer break to give my feet some air. This helps prevent blisters from the moisture side of things. It is also very important to stop and put on moleskins or athletic tape as soon as you feel a hot spot start forming. The only blister I've had was on day 1 when it was cold, sleeting, raining, and snowing and I was too cold to stop and deal with it. Hikers seem to be split on the issue of popping blisters, some say you should pop them and then wrap them and some say let them be. I've only had 1 blister so I can't offer much advice on the issue of popping it vs not popping it aside from that I went with the latter and it healed just fine. Most hikers seem pretty split on the issue.
It's all personal preferences, do whatever you can to keep your feet happy or else you're gonna have a bad time!