Thanks for the replies so far.
cdang wrote in post #15577995
You could add a 1.4x extender to the 17 and get almost 24mm but you cannot do it the other way around. 24mm would be more useful but.
Thats true, I almost forgot about the 1.4x TC on the 17mm.
I don't really mind the distortion too much on the Samyang, largely correctable, and the little that remains will not affect me much. Nor does the use of plastics bother me in such a cheap lens, I don't intend on using it as a football!
kawi_200 wrote in post #15578119
You can use filters on the 24mm, but you can't without some jerry rigged modification on the 17mm TS-E........
Therefore, option C isn't as good as option B.
Option D gives the most versatility. Of the options, I'd be tempted to go with option D. But the 17-40L first and see if you really want/need the Samyang 14mm. Also, instead of the 24-105L why not go for a 70-200mm f/4L IS?
Some good points there. I do realise the limitations of the 17 vis-a-vis filters. And yes, the Mk I 24 TS-E is not as good as the Mk II, but it is around half the price I did say taking $$ into consideration.
Indeed, option D is there simply because of cost and versatility, which usually dictates a lot of purchases! I know it will not win anything IQ-wise (except perhaps the 14mm in terms of sharpness) in comparison with the other choices. As to the 70-200 f4 IS, I already have one