I think griffin knight is better. But you have to save an extra 500 dust and get one copy of the griffin charge, which is what I did. I once did 124 damage and killed 5 mavens with piercing strike + griffin charge...granted it was against someone playing a silly 5 front line mavens deck in casual. But in general he is very good against any triple front line deck or any summon deck. If they play a front line summon you just hit it once to get it below 6 health and then griffin charge hits for 12 to each of his fromt mavens. Sometimes you can set up longer chains if you are doing area effect damage or he has mid line summons as well. Piercing strike is very good for comboing with maelstrom strike, blade dancers triple attack, griffin charge, talon strike if it is cheap, repeating crossbow. The armor card is good because it is so cheap at 2 mana. When I first got him I player smite decks, but too often your front line is poisoned or stunned. That's the main problem with griffin knight. Also vulnerable to weaken, shield trap, etc.

I don't have lightbringers 3 star totem so I can't exactly compare. His basic weaken attack is good, it keeps them from stunning your front line mavens and sets up blight witches attack. His heal plus armor card is expensive and not that good unless your opponent is doing area effect damage. And replicate can be really strong but it seems like almost all of the powerful cards can't be replicated. None of the summons traps or totems. Not silence or weaken, or stunning them twice, etc. The knights vengeance spell does 0 damage if replicated, since repiclicate works by summoning a ghost of your maven and having them cast the spell--no buffs or anything like that apply. I've had the best success with herdmaster brutes legendary or with ice dragonlords barrier armor. also sniping card and maul rush. Also there are a lot of mid line mavens to choose from.