I don't sleep in diapers every night, but when I do, the attire depends (pun not intended).
When it's warm outside, it's usually just a diaper and nothing else as I wouldn't be able to sleep due to the heat.
When it's colder outside it depends if it's a weekday or weekend. On weekdays, it's usually a normal diaper (ID Slip at the moment, but can be pretty much any decent medical diaper). On weekends, the diaper is almost always a Little Kings with a booster, as they are the most absorbant I have. That's necessary as they are accompanied by a locking onesie, so I can't just change myself once I wake up and my diaper is completely full. The extra absorbancy of the Little Kings combined with the booster enables me to keep using my overnight diaper without that much risk of a leak until my girlfriend, who usually sleppes 4-5 hours longer than me, wakes up and can unlock and change me.