I have created a Paragon XP Calculator tool and a Greater Rift XP interactive table
There is also a end of season Paragon XP calculator to work out your new non season paragon when the season ends.
Paragon Season Converter: https://enygma.ca/d3/paragon-season-converter
Greater Rift XP Table: https://enygma.ca/d3/greater-rift-xp-table
Paragon XP calculator: https://enygma.ca/d3/paragon-xp-calculator
I've created an excel file calculator for best GR level to chose in order to get most XP/hour ratio. Check it out and let me know what do you think
(description to excel in youtube video - link to download in youtube video description)
Hope it helps!