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Thanks!!! Very informative. I don't shoot much macro, but would like to learn some more.
That is a very tough question indeed. I actually own all of those lenses, so I'm familiar with their strengths and weaknesses (though the 40-150 is likely to be sold very shortly).
A lot depends on how you work. Do you prefer primes? Do you need macro capability? Do you need speed in the 45mm range? The 40-150 is optically very good in the close to medium range, though it softens towards infinity. From 5-15 feet, though, it's absolutely stellar (especially given the price). The 45/1.8 is an excellent lens, well worth its cost, and it's TINY. The 60/2.8 is near flawless. Very low CA, very sharp, compact, quick focus for a macro, good focus selection switch, weathersealed. Of course the 35-100/2.8 is going to be the most versatile with the fast aperture and range....it's also weathersealed and very well built. Internal zoom too.
Ultimately, for me, I'd probably take the 35-100, but it would be really hard for me to let the 60/2.8 macro go. I don't shoot a LOT of macro, but I do shoot enough to make it worthwhile to have a dedicated macro lens, and the 60/2.8 is hard to beat. I like and use my 45/1.8 a fair bit, and it's great for being super compact, though I've found myself using it far less since I got the 75/1.8 and 35-100/2.8. Part of that is because I prefer a little longer FOV for portraits than the 85-90mm (35mm) range, and so the 60/2.8, 75/1.8 and 35-100 are more appealing to me for that purpose, but I know a lot of photographers prefer that 85mm view over, say, 100mm or 135mm.
I've said that if I could only have 3 lenses for Micro 4/3, I'd take the 7-14, 25/1.4 and 35-100/2.8. If I was making a prime kit and could only choose 3, I'd choose the 12/2, 25/1.4 and 60/2.8. (sub the 45/1.8 for the 60/2.8 if you never shoot macro, just for the size savings and faster aperture).
Sorry for no real definitive answer....