I prefer 240, as being a bit further from 150, and splitting the geometric difference between that and my next lens, a 420.
The downside is that apart from old Symmars in No. 2 shutters, nearly all 240 f5.6s come in a Copal 3 - you pay a large weight and bulk penalty. I use an f9 instead. First an Apo-ronar in barrel, then a Germinar-W. At one stage a late multicoated Apo-ronar actually cost less on the used market than the Copal 1 shutter on it's own. Those glory days are gone, but they are still good lenses, and they still weight a lot less than a plasmat.