What are you basing this on? Are you basing this on the Shadow Warrior combat style against all of the other listed combat styles, or are you sharing your experiences with it against the common enemies of Skyrim?
Either way, I'll try a more realistic approach, as hard as it may be to imagine it:
Any combat style pertaining to Stealth is risky to go about, because your success rate can be based greatly on your environment; your literal settings, the time of day, what opponents you must face. A Shadow Warrior like yourself would obviously dominate in a dimly lit dungeon, with many dark corners, narrow corridors and big rooms. A typical bandit will be of no problem to you. However, if you were out on an open field, in the middle of day, and a dragon attacks... well, there goes your element of surprise. And you're definitely not one-hitting a flying dragon.
Every other style doesn't have to deal with this problem, because they don't rely on stealth to get rid of their enemies. Warriors just charge right in and kill everything and anything, against dragons of course they'll either have to wait until they land, blocking their breath in the process with their trusty shield, or if shouts are in fact allowed they can just use Dragonrend. Mages summon stuff and throw elemental balls of destruction, or whatever... same thing.
Now, let's say we're comparing these combat styles when stacked up against each other... the most fair thing to do would be to put these people in The Pit (Oblivion style) and see how they square off! Let's pretend they're all maxed out and get everything they can possibly get from their combat build.
Oh, crap... it seems as though the stealth-types have the short end of the stick again. In an arena? There's no place to hide. They're going to see you. No more element of surprise, and even if you happen to magically disappear, with a Sword and Shield Warrior's maxed out stats, they're like tanks. If they really wanted to be paranoid they'd just raise their shield up in a corner somewhere, and have their massive shield and heavy armor absorb the impact of a little dagger, if the Shadow Warrior manages to go unnoticed for that long.
However, if this battle happened to take place in a dark forest of cave, then the Shadow Warrior may come out victorious, because it's the surroundings that ultimately give them their lethality.
I'm not saying Stealth is not the way to be, and that it's the worst style. I'm just pointing out the major flaw it would have in certain battles due to it's dependence on the setting of the battle.