Those are quite different bikes.

The discs are popular for commuters now, but perhaps it is just a fad. Time will tell if they remain.

It really depends on your goals. If you're wishing to ride in group rides on the road, I'd probalby lean towards the Surly. If you're intending to take it off road and on gravel, perhaps leaning towards the Fairdale.

Also, keep in mind that there are a lot of used bikes out there. If your heart is set on steel, look for some used high-end road bikes from the 80's and 90's.