So I'm going hiking to either the Chiricahua Wilderness in Southern Arizona or Gila National Forest in New Mexico. I have no wilderness experience and will be doing day hikes alone (and sleeping in my truck). Do I take a handgun or rifle? Pros and cons of each would be appreciated.

Hand gun, never leave home without it. Easier to carry.

Must be a troll thread. OP going to carry a rifle around while hiking and sleep with it at night, locked in a truck.

Desert or NF in the southwest? Rifle. You've got coyotes (human kind), meth cookers (I've got stories) and critters. The first two pose a threat outside handgun range. Just take a lightweight pencil-barrel something on a good sling and be done with it.

Also, Gila NF has a bit of a reputation for weirdness, and is not the best place to be if alone and/or unexperienced. Cibola NF is better, in my opinion. More old mines to explore, if you're like me and enjoy walking a few hundred feet into a mountain to find cool rocks and old mining equipment.

Bear in mind that 95% or more of the hikers crawling all over the terrain are completely unarmed, and they only very very rarely run into trouble, and even more rare is running into the type of trouble that could be solved with a pistol or rifle.  Hypothermia, dehydration, and falls injure and kill people in the Wilderness areas; animal or human attacks are unbelievably rare to the point of being statistically irrelevant.  So statistically you are as safe with a rifle, pistol, or no gun whatsoever.  

If the gun is displacing other stuff like water or emergency bivouac gear, then you're less safe with the gun.

Of course if we go only by stats, we probably wouldn't carry.  If you're going to carry take your favorite pistol.

Chiricahua was a pretty tame family camping situation last time I was there.
Didn't fool around much in Gila.
Should be fine with a pistol hiking

I always carry a 9MM so it's with me on hikes, camping trips, canoe trips etc.. I've never "needed" it but it was comforting knowing it was there.

thanks for all the replies. i've settled on an HK USP 40 or a SW 686+

I would just carry a pistol. I would only carry a rifle if I can keep it concealed. That means either a short barrel or folding stock or both. If you want to do some recreational shooting that's cool. Anybody that crosses your path will probably be very nervous and remember you as that crazy guy with the rifle. If an area is dangerous rough to warrant it carrying an AR-15 I wouldn't be hiking there. I like watching backpacking videos on YouTube but when the guys start carrying full military kit with rifles I start to go: 

I take only a handgun, unless it's squirrel season, then handgun and 22 rifle.

We don't have many wild threats here, but people and dogs are my main concern.

I've been using a Hill People gear. Runners kit bag for the past few months and I really dig it.  Opens up alot of options on what gun you can carry comfortably

Glock 20, 10mm ...capacity plus stopping power