I have played all three clans quite a bit, and I have to say that !Gangrel is definetily the worst. I have a semi ok !Gangrel mono protean rush deck with lot of agg damage, amaranths, and gangrel conspiracies which sometimes wins games, but dies if it faces lot of prevent or s:ce. I also had quite a bit of success with Sebastian Goulet satyr deck, but that wasn't really !gangrel deck so much, as it used dom/obf/pro. Although crypt was mainly !gangrel (basic and advanced Goulet and Philippe,) with just couple DOM/obf support vampires off-clan).
!Nos I have made several quite well working decks with, best was probably group 2-3 midcap toolbox with some black hand tech (Teresita with watchtower four ride forth, and some corporal reservoirs and truth in inks), they can also make fairly decent stealth vote decks with group 3-4, as they have nice grooming chain of titled vampires, but that still never worked as well to me as similar concept with !malks who had the advantage of The Call and bounce.
!Brujah is the best of those three clans by far, they can do good vote decks, good rush decks, good bleed decks, about only thing they can't do is intercept. They also have lot of out of clan obfuscate in group 3-4 if you want to go that way. They have great midcaps in group 2-3, and great big caps in 3-4. About only problem I can think of for !Brujah is that their clan cards (apart from Gang Territory) are fairly weak.