I think it depends on why your buying it and what you're goals are.
My view is that CPX has a higher potential return but its riskier. Its basically all power generation and has some risk based on electricity pricing. It does have 25% of its revenue from renewables which I don't think they're getting enough credit for. It also has coal which is being converted to NG and is mostly Alberta which is a negative due to the poor growth although they're diversifying. They have one more year they've given guidance to raise the dividend 7% and after it will likely be a bit lower.
FTS is very safe and has something like 93% of its revenues which are fee based transmission and distribution. It looks like it can provide around a 10% return based on the current price and estimates which are based on their capital backlog. I think they have 3 or 4 more years where they given guidance to 7% dividend growth.