Para2. The why will come to you as you carry and use one for a while.
I have 9 of them (bring on the Maxamet) and it's my most carried model for EDC. Doesn't mean it will be yours, but I think you should get one, you will not stop hearing/reading/seeing/thinking about it 'til you do so just get it done.
940 is a great EDC folder, mines a -1 which is too expensive, but there a few good choices out there in G10/S30V 940's.
Actually I prefer the 943 but BM just won't come to the party with any upgrades for it
Tenacious is not in the same league (much as I like it) and I don't own the others you mentioned.
Also I am highly impressed with my Manix XL, ZT 0562 and BM 950 Rift.