Stances: The Way to Walk
You have 6 or 7 stances over your career as a Swordsage, assuming you remain pure. That 7th comes from the Martial Stance feat, which you may want if your build isn't overly attached to feats.
Flame's Blessing - Decent if you come up against fire enemies regularly, especially considering tumble is a fairly useful skill.
Stance of Clarity - At first level when you only have the one stance I don't like this. It works well against one person with an extra 10% chance of an attack missing for a 10% penalty against everyone around you.
Step of the Wind - Somewhat useful if difficult terrain is common, but do you really find it that often?
Child of Shadow - Keep moving about and you have 20% miss chance from concealment.
Island of Blades - Useful early on by making flanking a much easier option. If there's a party rogue you may want this, but if not I'd take Child of Shadow over this.
Stonefoot Stance - If you're a shortarse this is somewhat helpful, but even then I would consider Stance of Clarity a better option that this.
Blood in the Water - A stance good for multi-hitting with Scimitars and Similar weapons, but 1st level is competitive with all the stances around.
Hunter's Sense- It's like a Ranger's track. Plot advancement rather than a particular mechanic benefit.
Holocaust Cloak Decent, 5 damage whenever you take damage though is not ideal when you are fairly squishy with a 1d8 hit dice.
Pearl of Black Doubt - More AC when opponents miss you, but only for a round and only really helpful if you had a high AC from Dexterity, Wisdom and Armour.
Giant Killing Style - As always, very situational. I personally do not have many fights with larger enemies, so I ignore this. If you're a Halfling or something similar this is much better.
Assassin's Stance - 2d6 Sneak Attack is not bad for now if you flank people often. Average 7 HP a hit is fairly good in the early levels.
Dance of the Spider - Kind of meh as a combat option in comparison to Assassin's stance, since this is just a climbing ability. When was the last time anyone actually climbed a wall?
Crushing Weight of the Mountain - Grappling options! I don't like grappling and there's nothing really in Tome of Battle that supports it outside of this ability.
Roots of the Mountain - A Flat DR 2 is a bit meh at level 5 and the other ability: resisting combat maneuvers (Trip, Bullrush and Overrun) is not something that I think is very useful.
Leaping Dragon Stance - If you like jumping this is good. If you don't like jumping this is bad.
Wolverine Stance - One handing a two handed weapon is a really odd ability to gain. This isn't something you would swap in and out of unless you feel like carrying two one-handed weapons for normal fighting and two greatswords for just this stance, but that's just strange and expensive.
Oddly not every style has a stance here, no clue why, but it just reduces your choices.
Hearing the Air - Blindsense to 30ft and a +5 on listen checks. Again this is a situational stance and I would probably not pick it.
Shifting Defence - Only really good if you have high dexterity and the combat reflexes feat.
Step of the Dancing Moth - If you are sneaking around alone a lot maybe. But it's a difficult terrain thing when you've had earlier stances which solve the same problem.
Giant's Stance - Going up a weapon size with damage is not at all a bad thing. Some weapons benefit more from this than others. Consider how this matches with your weapons before taking it.
This time there's only once stance here and that's for Desert Wind.
Fiery Assault - 1d6 damage per hit at level 11 is not all that impressive, especially when you are focused on mostly a single attack from a maneuver per turn, unless you are very Tiger Claw focused. Even then, there are better stances
Prey on the Weak - Not at all bad if you tend to be the one dropping opponents. Really depends on the party composition.
Rising Phoenix - An interesting Stance and one of few that helps Two-weapon fighters. You get a flight, but not an especially useful one, since you're only 10 ft off the ground and if you make a full attack everyone in a square around you and deal 3d6 damage, which is only on average 10 hp, so it's not going to win fights.
Stance of Alacrity - Activating this stance is essentially a free action, since it states if you've already used your immediate action you can activate this stance. Two counters a turn to me is not that big, especially since your recovery mechanic is so awful, even with feats.
Ghostly Defence - Useless unless you have easy access to a miss chance. Cyan if you have easy access to it from a magic item or party member.
Balance on the Sky - A weak fly that requires you to keep a hand free. This robs you of half your strength modifier if you two hand a one handed weapon, forces you to drop or sheathe a second weapon and attacking without a two hands on your weapon is basically a non-option. In short, a 4th level spell at level 15 is not impressive.
Strength of Stone - Immunity to Critical Hits is nice, but it's a trade-off between defence and offence at this level. I prefer Rising Phoenix.
Wolf Pack Tactics - Kind of meh at this level. Aside from using is for flanking opportunities how is it going to help you? You have Shadow Hand techniques for precise positioning if you need it.