At 1080p24, I used to like 50 SS but had to switch to 60 SS for fluorescent lighting. At 60 SS, it seemed a tad bit fast, but fast SS actually helps apps like Twixtor and Timewarp. So 60 has become my favorite for 24p.
At 720p60, I use 125/250/500 SS depending on how fast subjects move. Faster subject, faster SS. Basically... there seems enough motion blur in shorter duration when moving faster which negates some of increase in motion strobe. In other words... my favorite SS varies.