I like the allegedly random - which allows a decent MC to avoid getting the two poets/toe-curlers one after the other (or even "wasting" the two really good turns one after the other). It also allows discretion over who gets the extra goes if there are any in the offing and allows them to give preference to the early arrivals ("You only sang to five folks, why don't you have another turn now") and that can be before a late arrival has had a first go.

But it's easier and/or a cop-out to just go round the room.

All imo...

~8^)