I would avoid a one with an electronic lock.
I both agree, and disagree with this.
A lot of cheap "safes", are nothing more than a metal box, and a junky electronic lock made specifically for that safe. Anything like this is a sign of ****.
Quality safes will come with a standard dial lock, and allow you to upgrade to a digital lock. The digital lock on these will fit into the same form factor as a dial lock (round), and is actually more secure than the combination dial. I'm quite familiar with the Sargent & Greenleaf 6120 digital lock, but there are similar quality safe locks from competitors like LaGuard.
And this is where I strongly disagree. Having a digital lock, it is so much easier to dial the combination, that you will use the safe more often, and not just find yourself leaving things outside of it "until later", because it just takes too darned long to dial in the combination.
Oh, and whenever a gun safe is rated by the number of guns it holds, think of dropping each gun in a sock, and cramming in as many as possible. That's how they get the number. If you have one box of papers in there, your 14 gun safe may now only hold 3.