The ultimaker doesn't have a purge column so much as a priming tower. It's much smaller and is really only there so the hotend that's been idle gets a chance to extrude a bit to get consistent flow before it goes to the model, similar to how people use a skirt to prime the hotend before starting a print. The ultimaker does however have completely automated bed leveling.

The BCN sigma I believe has an assisted bed leveling program, which does involve bits of paper, but I hear it's really well done. Overall I'd go for the sigma. The way the dual extrusion is done seems a bit more solid to me, the mechanic the ultimaker uses seems like it would introduce some slop. On top of that it can be used for batch printing. Other things are the fact it uses linear rails, has a full color touch screen as opposed to lcd and clickwheel and is properly open source.

Machines like the flashforge with two hotends mounted rigidly right next to each other are most definately going to involve a peice of paper, as you'll have to manually tune and adjust the nozzles so they are physically at the same height.