I've often written OCs with a yellow or orange lightsaber in mind, or purple if I want a little color. However, I'll be touching on my choice of yellow. I have always seen sources and lore explanations depict this color to be more of a independent color amidst the consular green and knight blue. Jedi Sentinels direct their focus on both lightsaber combat and defense against the dark as a knight would; and the study of the force, it's abilities, and upholding the peace as a consular would.
I myself am always questioning authority, rules, and like to understand why we do things we do. Am I an anarchist? Rebel? Or just a very independent thinking person? Maybe elements of all, but I can't see myself either choosing blue or green, or if we are following the current Canon; completing my trials on Ilum and getting anything other than yellow or orange.
I do also believe there is a difference between purple and yellow and the minds of those who own them. Purple is a color that often is used by characters that rely on or siphon power from the dark and light. Mace Windu is arguably the most famous practitioner, and as he used Form VII "Vapaad" its clear why he has a purple color. Or Revan, who's walked as both a Jedi, Sith, then the between. His reasons and story differ to Windu, but the explanation remains.
Yellow, and you could argue orange, could represent one who pulls from the ideological opposites rather than the power opposites. Making decisions the practioner deems worthy and acting on either pragmatic or independent thinking.
My choice is yellow/orange... most likely orange.