It depends on what you use. For me the 60mm is too close to the 80mm, therefore I bought the 50mm.
I have the 38mm SWC, 50mm, 80mm, 150mm, and 250mm. I do not take portraits so the 150mm is the least used lens.
Therefore I recommend that you look at my first sentence in this post.
I would keep all three. You need to shoot all 3 for awhile so you can decide for your self what you should do.
I recently bought a 60, and so far my results with it are amazing. Prior to that, the 150 has been the one on the camera most often.
If I were making that choice, today, I'd probably ditch the 80. Too much depends on how you like to work though.
If you don't have a pressing need to get rid of one, I'm with Fotch, keep all three for now.
That is a big if. Do you have to let go of one, or do you not?
i read a lot of interesting thought here.
actually, i have to let go of one (or two?) if i go through with the idea of getting myself a 35mm RF as a present :D
getting rid of my contax and canon 35mm doesn't bother me, since that's replaced by digital 35mm.
i don't like to have stuff laying arround unused, if i can replace it by less stuff that does get used.
i think i'll just have to find out for myself what i use least, or get least results out.
What I would do is to give one of the lenses to a friend to look after for a month or two and see how that feels. Then when you get it back, give them the next lens and so on. Which one was the least painful to loose? Which one where you most glad to get back?
Years ago I had that same kit with a 500ELM. I found it to be an excellent spacing of focal lengths. I would not part with any of them unless I had to, but if you feel that the 60 is not wide enough, or the 150 is not long enough, then that would answer your question. Otherwise, find another way to finance your RF.
Personally, I would sell the 80 last and the 150 first. However, this is just me. The normal lens is the most important lens for me. I also like a moderate wide like the 60mm quite a lot. When I use a telephoto on square format, I generally like to use ones longer than 150mm (e.g. 180 and 250), so I would probably sell the 150 first, planning on getting a 250 some time in the future.
I find it an impossible question.
I often carry just a two lens set, consisting of the 60 mm + the 150 mm.
If you have to be restricted to only two lenses, that is not a bad set at all.
The 80 mm itself is a great lens too: great quality, and very versatile. It would make a perfect one lens 'set'. Neither too short nor too long (which is why the 60 needs the 150 and the 150 needs the 60 in that two lens set - neither lens would make a great one lens 'set').
60 mm and 80 mm are close, but different enough to keep both in a three lens set.
But in the end, it all depends on what you like, want or need. What works for someone else may not work for you.
That sort of thing.
Here's my motto: The longer the focal length, the more boring the photographs.