I don't have an Intel iMac, but I do have one of the G5 iMacs.
I have a Samsung ML-2010 laser printer which I have found to be excellent.
Good quality B&W laser which is VERY reasonably priced (can be found for <$50 online).
It has a pretty small footprint & (I think) looks pretty nice.
My only complaint is that they advertise it as < $0.03 per page because of their "toner saver" function. However, on Macs, the "toner saver" function is unavailable, so I don't truly know what the per page cost is.
The others I was considering were HP, Dell & Brother - they all have comparable models, although I thought the Samsung was the best buy.
Good luck!