I agree with Vinnie. The more damage you do, it adds to your contribution to the battle, therefore you will always make slightly more for end plunder. Whether the extra payout is worth the mith cost? I'm not sure because mith cost is determined by your strength. For my alt I was able to purchase mith for 348m but on this guy it was 480m. Hope this helps!
It depends on what you are planning to do. For example I use the diamondiferous when atking the eb, and the abyssal blade to spy on people. Just look at the stats each one gives you and compare.