My opinion based on experience is to disconnect it. I store my truck in an unheated garage for about 5 months each winter. I disconnect the battery, but once a month I reconnect and start the truck, letting it run until I'm up to operating temps. Then I disconnect and wait until the next month. My battery is from NAPA and its 6 years old. There are no demands on my electrical system which is 12 volts and runs a generator.
