There are equally frequent buses from Higashi-Okazaki to Korankei (66 minutes, 800 yen one way) as there are from Toyotashi Station (42 minutes, 800 yen one way).
So, it comes down to whether Higashi-Okazaki or Toyoyashi is reached faster from your starting point.
Assuming you start in Kyoto, the fastest connection to Higashi-Okazaki takes 85 minutes and costs around 6000 yen, while the fastest connection to Toyotashi Station takes about 100 minutes and costs virtually the same. The latter connection does involve more train transfers, though, and can be considered less comfortable.
So, as you can see, the two approaches are almost exactly equally fast and expensive.
What I do not know, however, is whether eventual traffic jams make one approach preferable over the other.