Castrol Professional OE is recommended as it meets the WSS-M2C925-A spec, which, as far as anyone can tell, is a spec used to meet the extended factory-recommended oil change intervals. There's no other reason Castrol Professional OE is recommended other than for that spec.
If the cheaper Castrol Edge EP doesn't meet that spec (I do not believe it does), then there's no real reason to use it versus any other synthetic out there.
Mobil 1 EP is "suitable" for engines that require the WSS-M2C925-A spec. You can read more here:
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/1693619/1
I believe most here use either the Mobil 1 EP or the Gucci Castrol.
Can I ask why you take it to the dealer for an oil change once a year and change it yourself once a year? It's so easy to change the oil on these things, why not do it yourself twice a year?