I'm anti plastic... so I went keg. But that's just because I'm a little tweaked in the head.
I literally wrap a moving blanket (the blue/padded ones) that is folded up nicely, around my mash tun... and secure it with a super 'geto' bungee. It works like charm, with the also 'geto' insulated lid I have designed to sit in the rim of my mashtun. I get only .5-1 degree F drop.
That's how I figured out insulating my mashtun day one of my first AG brew... and it's simple and easy enough I've never invested any time/money/effort into changing my set up... My 2 cents.
