Races:

Core:
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Dwarf – Eh, not a terrible choice but if I’m going to sacrifice my movement rate I’d like to get something more useful for it
Human – Excellent choice. SS needs extra feats badly and always benefits from more skill points.
Elf – Ok. The boost to dex is nice, the hit to con isn’t. Proficiency with a ranged weapon pushes this up into the playable regime.
Gnome – As dwarf.
Half-Elf – Garbage.
Half-Orc – Garbage.
Halfling – A good choice. Boost to dex is noticeable while the penalty to str doesn’t hurt at all, boost to saves is always nice.


Psionic:
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Duergar – as dwarf. The invisibility seems synergistic but not enough to make me want to play them.
Githyanki – LA is rugged, but if you can buy it off or divert it to one side of a gestalt these become excellent choices. Mixes well with psychic warrior in gestalt.
Githzerai – LA is rugged, but if you can buy it off or divert it, these guys were born to be swordsages. Mixes well with Psychic Warrior in gestalt.
Xeph – Similar to Halfling. A fine choice if their “Burst” racial ability only takes a swift action to activate. No reason to take over Halfling otherwise.


Non-Core:
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Elf, Snow/Elf, Wild – if you have to play an elf, play one that doesn’t cost you 1 hp/level.
Lizardfolk, Poison Dusk – Bonuses to dex and con, solid choice. Gets better if you can buy off the LA.
Catfolk – big bonus to dex. Good choice, try to buy-off the LA. Gets better if you can.
Chaos Gnome – lots of useful ability boosts but LA is a turnoff. Worth a look.
Whisper Gnome – VERY saucy. No LA, boosts to all your best stats, useful SLAs and other abilities also.