My fav ? I am weird .. My fav is my Sigma 150 F2.8 Macro. I use it as a macro (of course) with extension tubes, as a Portrait lense, General Nature photos(nice bokeh), Event (Theaters), General Tele (with my 1.4 TC), Street photos.
As for Combination of Prime lenses.. In the film days(FX)? It depended on the individual of course. but you would choose 1 from each set below
* Ultra wides (...)
* Wides. (20,24,28,35)
* normals (35,40,50,55)
* Tele ( 85,105,135, 180)
* Long Teles (....)
Note that the 35mm was used by many as their "normal" - In DX the wonderful 24-70mm (equal 35-105) is just about a perfect all round lens and is probably well worth it if you are a person that likes that range. For me I like the longer end and wish Nikon (or any one else) would make a nice 28-105(120?) F2.8 dx lens (==42 to 160(180)) Oh well I can dream ..
PS: The 40mm focal length is known as the "sweet spot" and its was only "discovered" by a few photographers. its these fanatical photographers that have push up the price of the discontinued Nikkor 28mm F1.4..for DX use Go check out its price! You wont believe it! Maybe PMA australia will have a new 28mm dx!