I did a ton of research on this because I wanted to make an informed purchase. I talked to a number of different professionals in the industry, including locksmiths, safe dealers (true safes), etc. and got a lot of good information. What I am about to tell you might not be what you want to hear, but it is the truth based on what I was told and the research that I did. I am by no means saying this is absolute, but based on what I found out I believe this to be true. I fully expect that there will be many here who will say that I don't know what I'm talking about because they don't want to feel bad about their own purchase. It is not my intent to bash anyone or their purchase, but to try and help you pick what's best for you.
Now...with that disclaimer out of the way...
The typical brand name gun "safes" that you see in big box stores like Gander Moutnain, Cabelas, etc., are not really safes. Not by the Underwriter's Laboratory definition anyway. In fact, many of those big brand name safes aren't even tested by UL because the manufacturers know they would fail horribly in theft and fire protection. At best, if they were tested, they would recieve an RSC (Residential Security Container) rating, not a true safe rating of at least TL-15. I don't want to name specific brands, but pretty much any of the commonly listed names you can think of fall into this category.
Lets look at the two main factors that makes a safe good or bad; fire protection and theft protection.
Fire Protection
Most of the typical big brand name gun "safes" that you see at the big box stores use fireboard/drywall/sheetrock as their fireproofing material. It's all the same thing. This is a very poor way to protect your firearms from fire. This is because drywall is NOT a heat insulator, it is only a flame barrier. In other words, drywall will keep the flames at bay for a short time, but it does a very poor job at keeping the contents of your safe from heating to dangerously high levels.
Don't believe the hype or the so called "ratings" that these so called safes claim they will protect against. I wouldn't trust any of them unless they are UL rated. Most of the ratings are factory ratings, not UL.
Typically, you'll see a "safe" with a 30-45min at 1200F rating when they are using drywall. This should be a good indicator that your "safe" is not going to do much to protect your firearms in a fire.
Theft Protection
Most of the big brand name safes will make claims about the number of bolts or the thickness of the door as an indicator to how "theft proof" they are. What they don't tell you is that although the door may be relatively thick, the walls are usually just sheet metal. These sheet metal walls can easily be cut into. Anyone who has half a brain and wants into one of these types of safes, so long as they don't have to worry about noise, will be in within a matter of minutes. This includes just about every big name safe you can think of.
This is where, once again, the UL ratings come into play. There are several ratings: RSC (Residential Security Container), TL-15, TL-30, and TL-60.
RSC is the lowest rating. IIRC this rating means that a knowledgable theif will have to take 5min to break into the "safe". Not much protection, but better than a lot of so called safes that aren't even RSC rated by UL.
TL-15 is the first true safe rating. As the numbers indicate, it takes a knowledgable theif 15 minutes to break in. TL-30 is 30 min and TL-60 is 60min. TL-15 and TL-30 are what you want if you want a
true safe. From what I've read, TL-60 is extremely rare and only the most astronomically expensive safes are rated this high. Expect to pay about $3000 to start with a new TL-15 safe.
I talked at length about this with a guy who deals in true safes, and only true safes, on another forum. His opinion was that the only safe worth buying was a true safe, something TL-15 rated or better. Now, I believe that he is a little biased, since he only deals in these type of safes. However, the product he has certainly is worth the money if you have the cash to spend.
As an example, he quoted me a TL-15 safe that was $3300. It had 1/4" thick plate steel walls, 1/2" plate steel door, 2" thick concrete under the plate steel all around, and a final inner layer of 10 gauge steel. It weighed 1300lbs. It was UL rated at 1800F for 2 hours! Not factory rated, but torture tested by UL. Now, ask yourself, do any of the typical gun safes out there even compare to that? Certainly not, but they certainly don't cost that much money either!
I wasn't satisfied, so I continued my search. The safe I finally ended up looking at was somewhat of a compromise. I didn't want to break the bank on a true safe, but I also didn't want something that only afforded me "ignorance is bliss" protection. The safe, or RSC rather, that I settled on was the
American Security BF Series. I found the BF6030 model for ~$1500, ~$1700 delivered to my door. It has 1/2" plate steel door, 10 gauge steel outer body with poured concrete between the outer wall and an inner steel wall, for a total wall thickness of 2". It weighs nearly 900 lbs and offers true UL fire rated protection of 1275F for 90 minutes.
If you are looking for any amount of serious protection the American Security is what I would go with at a minimum. If you can afford it and really want true theft/fire protection then you might as well go for a true safe. Otherwise, if all you want is to keep kids out and very marginal fire protection any of the big name stuff, or big box store stuff is fine. Just know what you're actually getting before you buy.
I hope this helps. If you'd like to know who I talked to about this you can IM me and I will get you the info of the guys that I talked to.