In theory, "better" depends on use. Diode Vf goes up slightly as Vrrm goes up.
In practice, datasheets don't specify this; typically the 50-200V parts are specified together, and the 400-1000V parts together. It's not clear if, by getting a 600V part instead of 800V, you're getting a slight edge on Vf, or conversely, if they're actually all the same Vf and Vrrm in that set.
If Vrrm satisfies your application, don't worry about it.
Tim