What type of Undercoating should I use?

[Fiat88]

I want to replace the undercoating but I'm not sure what's a good diy type to use. Should I use a spray can type, roll on type, or brush on type? I knew there are a few different types.

[htchevyii]

I like the rubberized type much better than the tar stuff, but have been using SEM epoxy bedliner alot. Tuff stuff and will look good forever. I use the spray gun or spray can 'cause I don't like brush strokes.