Valve cover Hole questions

[blazerboy_4life]

So im looking at a new set of aluminum valve covers on ebay cause I like that raw aluminum look but Im on a budget. The ones I have now are orange painted Chromes and leak like nobodys business. The ones I like have no holes in them but they offer a pair for the same price that have one hole each. what are the pros and cons of running valve covers with or without the holes in them. Are the ones without just designed to be drilled where i need them? As always thanks for the advise everyone.