Well that's a personal choice I guess.
Six direction method imparts a sphere -in theory- but it uses the mind/ body in specific ways to manifest that feel. Think of one point as a model. There is no sphere, so talking about how strong a sphere is and the qualities of it are waste of time. You cannot make a sphere out of your body and if you try, you will fail in innumerable ways. Likewise there are innumerable Aikido people who claim to use Tohei's model or to understand ki who have nothing unusual by way of power. Their one point is sort of okay under dojo conditions but fails under stress. Using the sphere as a mechanical model is inefficient. Describing what the body must do to manifest six directions is an exacting model that is a success. A success with a history.
Remember, Ueshiba was talking about the body...and not the "spiritual" things people erroneously assigned to his physical principles.

Why?
The really wonderful question is why does six direction blow up the push/pull model? The answer is simple but very hard to grok at first, harder still to do. Most simply cannot see how you could be in agreement with someone and totally neutralizing them at the same time. Moreover what that does to your own body to strengthen it and how? And if you understand THAT then you understand that making aiki between you and them like the oft quoted four legged animal between you and someone else was flawed from the start. Takeda, Sagawa, Ueshiba, Shirata had it right.

There is no debate in person. So I prefer to debate in that venue, where teachers have to provide proof of their understanding in an inescapable venue under stress.
Dan