At one time I was certified by both ARRL and W5YI as a VE. For various reasons, mainly cuz' I forgot to renew with W5YI, I'm only certified with the ARRL now. I think the ARRL has more VEs than the others, but that's not because of any 'special' reason, they are just more well known. There's no particular benefit to any of them.
Okay -- I am a little jealous -- the other night during testing we had a guy come in a upgrade to Extra -- he only missed 1 (as fate would have it it was question 49). So far I think that is the best Extra test I have ever seen.