I would think 5 10oz bars would be easier to sell in a crunch. If you're talking about Silver or Gold.
In the long run you will pay less of a premium for the 10oz bars to you will actually get more for your money
once 50oz would look very cool as a doorstop. I would imagine selling it would be a lot more trouble than smaller units.
And if you want to sell just some of your PM you can, you don't have to find a buyer for the whole lot. If I want $200 I can sell one 10 bar of silver and still have 40 oz stashed. With a 50 bar I have to sell it for $1000 and have all cash and no silver. (I'm using rounded numbers, don't beat me up over the current spot value.) No problem, I've got one.