I work in Canary wharf, hence survey response is: Both
Morning: via London Bridge
reason: ELL stops at Canada Water (one stop before Canary Wharf), and it is already nigh on impossible for connecting passengers to get on. ELL will only make this worse.
Afternoon: via ELL
reason: Will hopefully cut the journey.
Ditto for the same reasons. Canada Water was always a problem in the morning prior to ELL shutting down for the extension. Any benefit of shifting a proportion of people onto the ELL in the mornings to Canary Wharf will surely be lost in swathes of people continuing to get on the Jubilee line at London Bridge (and earlier) from every other direction anyway.
The evenings might be different however. Perhaps we've stumbled across some of the "justification" for our impending reduced preak overland services in the evenings but not the mornings.