I am sure all these tires/sizes are good and they all look good in different ways. Here is some of the logic I am considering. If there is a flaw point it out.
An 18" 335 30 18 appears to be wider than a 295 50 15, it puts more rubber on the road.
Here are two photos with the tires I am considering, they are as close as I can get to the same camera position.
They are similar looks, both good but I am leaning towards the 18. There are a bunch of tires for the 18" rims.