This may have been true several years ago, but I find the entertainment value has swung hard to the south. There are many reasons for this, including the fact that the NFL has changed its game and become much more pass-oriented in recent seasons.
But as much as the NFL game has improved, the CFL product has deteriorated. Our timing rules are far inferior, and inconsistently applied, for starters.
Intra-crew communications for officials are terrible and archaic here, resulting in way too many on-field conferences, especially compared with the Americans' communications. Likewise with the replay systems... theirs works and ours does not. These deficiencies in officiating tools really adversely affect game flow, affecting entertainment value.
But the biggest factors by far stem from the CFL's CBA-enforced lack of practice time. This leads to a lack of cohesion and refinement, especially on offense, leading to vanilla play-calling. This lack of practice also slows individual player development, meaning fewer spectacular plays. On the defensive side, calls are also more vanilla. Anecdotally, I back this up by saying I am a former high school qb (NCAA scholarship offer), I can watch a CFL game and read the defense, anticipating blitz and read the coverage. When I watch an NFL game, I cannot do this... their defenses are far better disguised, more complex and more nuanced.
But the biggest result of the lack of practice is glaring to even the most casual of fans... flags. Flags, flags, flags. And its not all on officiating. Players don't have enough practice time to perfect their craft, so they commit more fouls and we see more flags. This has completely destroyed game flow in the CFL.
Now add parity issues. The NFL has weak divisions. But at least its not always the same divisions. Weak and strong divisions rotate. In Canada, its always the same division that gets trounced. Also, in the US, they have enough teams and a large enough playoff pool to weed the weak ones out. If a team with a weak record does get through, they have to earn it through multiple games. In Canada, a weak team can get lucky and end up skating through. As such, we end up with a lot more undeserving championship teams, cheapening the meaning of the Grey Cup.
I do not think the NFL is perfect. Far from it. I actually like both forms of football, and I appreciate their differences.
And, once upon a time, the CFL was the more fun game to watch, even if the big name and big money athletes were in the States. But that no longer applies. The CFL on-field product has declined precipitously, and the ratings and attendance numbers back up my position on this.