I recently analyzed around 6000 shots taken over 10 weeks at South America with the DX lenses I previously had (10-24, 35 and 55-200). The 35mm equivalent focal length usage as follows:
15mm: 33% (almost 2000 shots!) 40mm: 13% (36mm rounded to 40) 50mm: 13% 80mm: 10% 300mm: 9% (majority of these taken at Galapagos Islands)
As an amateur I shoot mainly landscape, travel, candid portraits, astro and street. No birds, no sport (as mentioned in a previous post). I have so far obtained D750 along with 35mm, 50mm, 85mm f1.8 primes which seems to support my usage behavior however I'm yet to decide on the following:
> 20mm f1.8: hopefully this prime will fit in nicely although not as wide as 15mm. > 14-24mm f2.8 vs 16-35mm f/4: which wide zoom do you think I will benefit the most from? I have been shooting at the edges (15mm & 36mm) mostly based on usage data. 16-35mm would have shareable 77mm filters with 20mm (Hoya: CPL, ND 3-stop and ND 9-stop). However, if I have 20mm and 35mm primes already I am not sure if 14-24mm would be a better option for me? > 70-200mm f4 + 1.4TC III vs 300m f4 PF: I didn't have to use 300mm too much except at Galapagos Islands. I'm however going to Africa next year and wondering how 70-200mm f4 at 280mm (with TC) compares to the 300mm f4 PF? I guess 70-200mm f4 might be better all around lens still.