I usually go with 720p, most of the time there's no noticable difference between that and 1080p. The file size can often be much smaller as well, which means streaming/downloading uses less bandwidth and buffers faster.
I only have a 1080p screen anyway, so maybe it matters for bigger resolutions but for me the quality is pretty much the same. If I really anticipate an anime or if it's a movie, then I might get the 1080p version just in case it looks better.