The red line - the normal route.
The advantage of choosing this one is the less steep approach in the end of the route. From the pass at the horizon, to the summit it's never more than 40 degrees. The problems you may encounter is very hard winds on the pass and deep snow.

The blue line - the crater rim variation.
It's more direct and takes less time. On the other hand there are some steep parts, especially going from the left hand side of the crater rim to the top of it. Make sure you're really acclimatized choosing this route. There are some tough scrambling/easy rock climbing in the end.