Dial.
I have never seen an electronic lock that had the strength of a dial lock. All steel tumblers, cams and rods are going to work for hundreds of years and have. On the flip side, I have seen batteries fail and then leak in an electronic lockpad, causing the entire unit to be replaced and the inside of the door and lock to be cleaned, a huge expense. Also, many electronic locks have a key bypass for the eventuality of a lack of power. This, to me, is a security weakness, because it gives another way into the safe that doesn't need to be there, a key that needs to be separately secured and just adds to the number of weaknesses allowing someone to exploit to possibly break into this safe.
Steel doors, one dial, very few, all known ways to defeat it, and they all are expensive to execute and take a long time. Not so with electronic locks. The safe can be defeated the same as the dial lock, but it can also be hacked, more likely to be videographed, print lifted, fluoresced, or many other of the keypad defeats. An electronic lock is a gimmick that someone thought would help sell safes to the techno-geek crowd, and it worked. But it does not make them better or safer or harder to crack.