Yeah. It depends on the rift really. Most of the time it's better to reset and open a new one, A) You get a small amount of XP for each one closed and B) You're going to run into just as much stuff in the new rift, plus another guardian (and thus, more blood shards).
I would argue that chances for legendaries/set/chests/goblins is largely irrelevant, as long as you're in a rift be it the old one or the new one, you're going to be running into those things anyway. The only thing it costs you are rift shards, and blasting through normal bounties you can farm out about 25 in under an hour.