Northern Lights Tours

Please consider that Northern Lights are not guaranteed. They do not occur every night; it depends on the solar winds, and even when they are active, you need clear skies to see them. Note that the Iceland Air tours describe it as a Northern Lights "hunt".

http://www.icelandair.us/vacations/package/blue-lagoon-and-northern-lights/

So with that in mind, I would choose the tour that offered the best match in terms of activities that interest you, so you will enjoy your time even if the lights do not appear.

Lola is absolutely correct when she said this:

Please consider that Northern Lights are not guaranteed.

My daughter, who studied in Scotland, heard about the Northern Lights sightings one day,
So the following night she & a bunch of her friends went to a high point of the city, where they stayed up very late, hoping to see the lights, but they did not...

I once witnessed the Northern lights while flying home from the UK, it was surreal!

I hope you get to see them too!

I lived in Fairbanks, Alaska, one of the prime viewing spots, for seven winters.
I can assure you that it is not an everyday occurrence. When the lights are good, it is is incredible--- but that is rare. But that is when all the promoters take photos --- to make it appear that it happens every night ( which it does not).

Echoing others. Auroras are due to solar flares. This usually occurs on 11 year solar cycles.
The last solar maximum was in 2014 and it was fairly weak. That doesn't mean you won't get auroras but the chances are less.
If going on a tour look for companies that provide heat, hot cocoa, and stories. Sitting outside in the cold is unpleasant if unprepared.
Good auroras are totally worth it though.

Edit: looks like they went crazy in Iceland last night
http://spaceweather.com