I'm not 100% certain, but AFAIK, if you are a Koodo prepaid customer, you won't get access to their faster LTE network. That would mean you would miss out on the LTE capabilities of the S4. Probably the equalizer IMHO if you are comparing a handset with 3G capabilities (Nexus & S3) vs one with 4G/LTE (S4). Buying a non-LTE enhanced device probably makes little sense any more since you would already be behind the curve per se. Keep in mind that in 2-3 yrs something faster & better will always be coming out, so your point is moot in this regard. Buy what you need now and don't expect it to keep up with the latest phones in 2 years to be more realistic in your gizmo acquisition.

Battery life on all is disappointing unless you are a infrequent user IME. All are very capable rigs though. BB is nice but still so new and has less of an app ecosystem vs Android or iOS obviously. For this reason it makes little sense for many users to go BB any more.

There's also a very Canadian-centered wireless forum called howardforums.com, which you might want to check out IMO.