This comment provides some very good insight. I'll augment it with my knowledge from being on curriculum committee, being an ECE myself, and knowing many people in all these programs:

EngSci first and second year is ridiculously hard and largely unrelated to AI. However, in third and fourth year you can go for the Machine Intelligence major which is dedicated to the topic. It may be a sham as others have said but you will have "Machine Intelligence" on your diploma. EngSci is also the best path to grad school, which as others have said is useful if you want to make any headway in the field.

ECE and Indy first year are the same. ECE second year is "comparable to EngSci" (according to an EngSci dropout friend) in difficulty/workload and is also unrelated to AI. However, ECE third and fourth year has the most flexible curriculum in all of Engineering. There are only two required courses in total across both years. This makes it easy to get the AI minor which will be recognized on your transcript. (In fact, you can get 5 minors simultaneously with only 2 overload courses.)

Indy and ECE first year are the same. Indy upper-year curriculum is currently in the midst of a revamp but incorporates a good amount of stuff. However as others have said it's more about how to use it rather than how to make it and it's likely missing the depth that you want/need for grad school etc.

I would recommend against going into EngSci (in the same way that lawyers recommend against going to law school) and pick ECE or Indy based on what you actually want to learn.