It does not matter.

If you follow MB's recommendations on weight of oil (which you are) the brand makes no difference. None. Don't let the "oil Nazis" or clever marketing/branding fool you. Oil is oil. If you change it hot and change it often it does not matter what brand you use.

FYI - I use Rotella as well. It is cheap and readily available at WalMart. I pick up two gallon jugs there every couple months.