I have both, the 18-55 is mainly for night photography, and taking wave shots in Hawai'i because I picked up a Hoya 58mm ProND1000 Filter, 10 Stops (3.0) to get the effects that I want on the waves and water. I use the 18-135 quite a bit, both in normal and very low light, here are a couple of 18-135 hand held examples shot this last Sunday at our church gathering at Canvas Church in Kalispell, MT. Then yesterday while I was in Starbucks, I used the 18-55 which did not attract any attention from anyone while I was using it. And then at the Holiday Inn Express last night, while my wife was shopping at a local store.
So while heading over to Hawai'i this Saturday, I will be shooting some indoor shots at the different airports, and different static shots looking at sharpness and over all image quality. So far, I am very impressed with the X-T1 and either of these two lenses.
18-135
Crystal said, this is my bad side Jon Crystal Lynn by Jon Erdmann, on Flickr
The stage is 50 feet from where I am shooting from
Celebratiion by Jon Erdmann, on Flickr
18-55
At the counter in Starbucks
Starbucks by Jon Erdmann, on Flickr
Holiday Inn Express
Holiday Inn Express by Jon Erdmann, on Flickr