Funny, I challenged myself to answer this, but it's "the right one for the image". I do like shooting ruined things with the RB 65mm though. When my primary income was fashion shooting, it was the 180 on the RB (about the max I could handhold) and 85mm to 200mm on the Nikon.
Really, it's "the one I have with me", because I've gotten some of my favorite negs with my old fixed-lens Minolta HiMatic (7s). Because it's a simple camera to throw in a backpack so I tend to have it with me on a trip. And that lens is just the freakin' SHIZZ as the kids say.
I shoot a lot of video with my newer camera bodies, and that's where I find I have more prefs. The Nikkor 28-70 2.8 (beastly thing) is on their a lot. Saves a lot of time on set and looks pretty. I use the 85mm 1.8 AF for interviews, it's pretty magic on APS-C/Super-35. Those two really get the most workout.
One cool thing I'm finding is my very-modern, mirrorless 4K body - sweet jesus, old 1960's Canon FL glass is kinda magical on that thing. Everything gets a little "rembrandt-ish". Just really beautiful color, and wide-open, it's like some perfect mild diffusion is on everything but the subject. Amazing that I can build a set of primes for next to nothing (other than the 85 - sucker is pricey!!!)