Best sealing valve cover gaskets
A lot of times it’s not the gaskets fault. If you’re using stamped steel make sure that they’re not warped from over tightening. Use pressure spreaders under the screws to distribute the load. Make sure there’s no metal to metal contact. Cast aluminum sometimes interfere with aftermarket aluminum intakes and you have to file the inside ledge. Make sure all those things are right before you blame the gasket. I’m using regular cork ones with a cast Mopar valve cover. Never had a problem after torqued and retorqued a couple days later.