Best forms for Alter Self

[Twilight Jack]

I'm running a very low level game in which the current villain is a specialist transmuter. As the PCs are all currently level 1-2, I have placed her at level 3 (I don't intend for her to die at this stage of the campaign and to increase in levels with the PCs, for a recurring nemesis).

Currently, her best spell is alter self. As a humanoid, what are some interesting forms for her to take to present a good challenge to my PCs? I am sticking to the core books, along with the Complete series, the SpC, and the various MM I-V. I don't want to break the game here; I'm just looking for some tried and true humanoid forms that can pay decent dividends while she's still nearly as inexperienced as the party.

Don't worry, she's got a party of her own for the time being, so she doesn't need to take on the PCs alone.

[Tukka]

Troglodyte for the +6 natural armor. In a watery environment, locathah for the 60 ft swim speed and +8 to Swim (could be a useful way for her to make a quick escape in the right situation).

If you want this character to be a recurring villain though, be careful about letting your PCs even get near her if they know she's an enemy. With some determination, creativity and luck, the PCs will find a way to kill her.

Edit: Also perusing the list, the varag looks pretty good too. 60 ft. speed and +3 natural armor -- a somewhat more rounded choice than the trog.

[Hawk7915]

Don't have anything but SRD in front of me, but a few choice ones from there:

Lizardfolk - A nice skill boost, natural weapons, and a juicy +5 natural armor. Combo with Mage Armor and Shield for a lizard transmuter with better AC than most fighters at this level.

Locathah - have her corner them in an aquatic setting and use this form; decent armor and a 60' swim speed.

Troglodyte - A whopping +6 natural armor, and a few more natural weapons.

Perusing a few more forms from other sources:

Varag (MM4) - a great stealthy choice: speed and skill boost are awesome.

Raptoran (RotW) - not quite flying yet, but gliding (I think), some awesome skill boosts, and good natural weapons.

Crucian (sandstorm) - +8 natural armor, Jebus.

Something with flight: Air Mephling? I dunno, there has to be something...

[Tukka]

And of course, sometimes one of the better forms you can take is something that effectively works as a disguise. Of course, disguise self is more specifically tailored to that purpose and better in some respects (it lets you change the appearance of your clothing/equipment and is lower level) but has the disadvantage of allowing a Will save on interaction.

[Cyclocone]

There's an entire thread devoted to this here.