All of your name brand safes - Liberty, Champion, Ft. Knox, Stack On, etc. are essentially the same. About the only real difference will be in the type of locking mechanism in the doors, possibly the shell thickness (and you are only talking about gauges, so it's not a huge difference), color, interior options and the various fire ratings.
It's really hard to go wrong with any of them.
What I will tell you from my (limited to one safe purchase so far) experience:
1. Don't think about what you have now. Think about what you'll have 10 years from now, then double that number. Size your safe based on that. These things magically fill up, and fill up faster than you can imagine.
2. As mentioned above, advertised capacity is pretty much a lie. Take the advertised capacity and multiply by .67 for non-scoped rifles and shotguns, .50-.55 if you have predominately scoped guns. Sure, you can get the number they claim into the safe, but it's far from ideal or user friendly if you do (trust me, I know).
3. Fire rating - get the longest and hottest you can afford. Odds are if your house is on fire, the contents of the safe are going to be damaged anyway. Fire rating prevents them from being completely destroyed.
4. Construction - all of them brag about having 4" thick doors with X number of locking bolts. Which is great if a bad guy is trying to break in through the door. The weakest point of any non-custom made safe is the sidewalls, top and back. And 15 minutes with a skillsaw and an abrasive blade and you can just about cut the side off of one because they are all mild steel, relatively thin (most are less than 1/4" thick) walls. Keep that in mind for....
5. Location - put it in an area that makes accessing the sides as difficult as possible. Yes, they are pretty pieces of equipment. Yes you will love having one (hey, it's manly stuff and holds guns - this is good stuff here). But don't be that guy that advertises their safe in the middle of your bedroom or office. That just makes it easier if a bad guy wants to break in to get your cool stuff. Put it in a closet, and if you can - bolt it to the wall or (preferably) anchor it to the floor).
6. Lock - dial combo vs. digital. Meh, personal preference. Dial combo looks a lot better and is more classic, but is also more difficult to use versus punching in an electric lock code. If you get in your safe fairly regularly, get electric. If not, either works just as well.
7. Weight - manufacturers love to brag about how much a safe weighs. Problem is that you can move a 700+ lb safe with 4 sticks of Sch. 80 PVC pipe or a hand full of golf balls relatively easy. I know - been there, done that. Three times actually. So don't get fooled into false security by the weight advertisement.
tl;dr - buy the biggest you can afford, highest and longest fire rating you can afford, and put it somewhere hard to get to when you get it home
