Two kinds of butane lighters...soft flame and torch flame. Zippos use lighter fluid and are all soft flame.
Two kinds of rim darkening...sooting and scorching. Soft-flame lighters and matches will soot the rims, that is, the darkening is a deposit of carbonized fuel on the rim. Torch-flame lighters will literally scorch the rim, meaning burn the briar and turn it to charcoal.
You can safely use a torch flame lighter, but you have to bring the point of the flame straight down from above the pipe, directly at the center, and draw a couple quick times and withdraw the lighter. In fact, if you want absolutely no rim darkening, using a torch lighter in that manner is ironically the best way.
Personally Idgaf about sooting the rim, I just want the pipe lit quickly and with minimal effort. I always smoke outside, therefore a Zippo is the only one that fits the criterion. If I smoked indoors, or where I could easily shield the flame, I would use a disposible soft-flame butane lighter...minimal hassle. Matches are fine too, but unless you're a slob you need somewhere to put the spent ones.