Two things to offer:
First, if at all possible, steer clear of the models with the digital key pad. These key pads do fail and when they do, you are looking at deconstructing the safe. In reality on the lower end safes, this is real easy with a sawzall, hammer and pry bar. Really not even that time intensive...
Second thing is what I have viewed from my profession as a fireman. Water is the main thing to worry about in most residential fires, (if you live in an urban or suburban area). We use lots of it to put a fire out and the low budget safes just do not have the gasket materials to keep it out. Also most folks seem to put their big safes in the basement or the first floor where the excess water will collect. If able, put your safe on an elevated platform. Even 6" would be enough.
In the end, I think the best thing is insurance in depth. A good safe, but also a good policy to protect your firearms collection.