Building my unholy tinity... Which one next?

Definitely get the 16-35 f4 next. It's a truly great lens and far more versatile than the 135 which is essentially just a portrait lens. I have both and to be honest the 135 almost never gets used, mainly because i prefer using my 85L for portraits.

Heyy got the 16-35Lii, 50L and the 135L.

The 50L gets used most together mit with my 16-35, but im gonna sell the wideangle to get the IS version.

To me you dont need anything more? Also youre stating you want a wideangle but you already own the IS version of the 16-35?

Edit: Ohh sorry i didnt read your first part right. Well then get waht you wrote because 16-35 is a super focal length range and pairs very very well with the 50L. However the 135L is more or less only for portraits, so if you want to get something more versatile on the long end, get a 70-200 f/4 or f/2.8 or a 70-300L (also recommended as i like mine very much for long stuff). But dont expect the zooms to behave like the 135L, that lens is simply one bit more magic

Get the 135l for family pictures
50l inside family and 135l outside family...now mom is happy. Then get the Samyang/rokinnon 14 for uwa. It's a great and inexpensive lens. " look dear at these beautiful pictures of the kids. I really wanted the uwa lens but these pictures of the kids are amazing with the 135L. But I miss taking pictures of landscapes and found this lens on sale for 275. It's manual so it will be harder to use [not much in this case] but it's almost 10x less than the canon one. "...I'm just saying now I have a 70-200ii and a rokinnon 14 2.8l