Why Semi-Auto, why not get a good bolt rifle!
Here's an explained list for the benefit of those who may be unfamiliar with firearms.
1. Lower recoil for a given caliber. This is a definite plus as you move up in caliber. Bolt, lever, pump, and break action firearms dump ALL the recoil through the stock into your shoulder. A semi-automatic uses some of the energy to load the next round. Having shot all these except the bolt action, it makes a difference. I'm not small by any measure but I wouldn't want to use a 12ga pump or break action shotgun for birds. An afternoon of that and even with a recoil pad on the gun will give you a bruised shoulder.
2. Higher magazine capacity. Do I expect to need it except to cut down on interruptions to reload at the range? No, but it's nice to have if I do.
3. Exchangeable magazines. Some bolt and lever actions use a fixed rotary magazine. Loading a fixed rotary magazine rates high on my list of top PITA's ever.
4. Cost and availability of ammo compared to most bolt action rifles. Decent to good quality 5.56mm ammo is readily available and is CHEAPER than 22 Magnum (if you can find it) as of last night
5. Customizability. If you can think of it, someone probably makes the accessory for an AR. Even some that make you scratch your head & go "Hunh?"
6. Adjustability. The AR and similar Modern Rifles can be adjusted for comfort to fit a range from a small woman to a large man in seconds and reversed just as fast. Doing that with most bolt action rifles requires a permanent stock modification & is not quick.