Metal
Advantages: durable, no risk of absorbing flavours
Disadvantages: may scratch certain cookware
Wood
Advantages: doesn't scratch, looks nice
Disadvantages: can wear down over time, can sometimes absorb flavours
Plastic
Doesn't find a place in my kitchen other than a rubber spatula for baking.
Silicone
You didn't mention this, but I like it, because it works like rubber but can withstand high temps (brushes, spatulas)
I think the answer really depends on what you cook. A good basic set might consist of a wooden spoon, a spatula that can handle heat, a good ladle, and maybe a set of tongs or chopsticks. You'll quickly learn what you wish you had to make it a little easier.
Modifying your original terms:
Size: 2-3 quart/liter. I consider 2.5 quarts to be ideal.
Material: Two options: hard-anodized aluminum nonstick, OR stainless-steel interior/exterior. With stainless, it should have either an encapsulated aluminum disk base or a tri-ply construction (aluminum layered with stainless)
Bottom: Thick is good, and you absolutely must have aluminum here for conduction
Handle: stainless is good, as long as it stays relatively cool. The handle absolutely must be riveted on, with thick rivets. Screws, glue, or welded handles do not last long-term. Tack-welded handles are the bane of the restaurant I work for right now; we've had several handles snap off in the last year.
Additional things to look for:
Weight: HEAVY. You want fairly thick cookware for even heating, but most of that weight should be from thickness of the aluminum disk.
Design: A flared lip around the pot, to facilitate clean pouring.
Shape: I'm partial to shallow designs, which flare out at the top. Although it's nonstick and not stainless, I love my Calphalon Contemporary shallow 2.5 qt saucepan for it's extra-flared design. This lets it transmit heat more efficiently from the range, and allows it to safely hold a larger capacity of food. It also allows for faster and cleaner reduction of sauces.
Lid: TEMPERED GLASS with a handle on top, and a flange to help seal tightly on the pot/pan. Tempered glass is very durable and lets you see the progress of your cooking without releasing the steam. The handle also remains cool, so you don't burn yourself on it; this is the second problem I have with solid stainless lids on many premium cookware lines (All Clad, and most manufacturers' tri-ply products).
Best Answer
You should get a carbon steel wok with two short handles (not one long handle).
You want the steel to build up a patina of oxidized oils, which rules out stainless steel and aluminum and non-stick. You could conceivably get a cast-iron wok, but those are really heavy.
You want the two small handles so you can pick up the wok, but you don't want long handles that will dump hot oil or food everywhere if you bump them. Unlike a saute pan, you don't toss the pan, you toss the food. (Tossing the pan pulls it away from the flame, which is bad when stir-frying!)
Your best bet is to go to an Asian grocery. You'll be assured of getting a product at a good price. Shouldn't cost more than $25, I don't think.
Oh, one other question is what sort of stove you have. If you have an electric stove, (a) I'm sorry, and (b) you have to get a flat-bottomed wok. If you have a gas stove, you can either get a flat-bottomed wok or a round-bottomed wok, but the latter only if you get a wok ring that holds the pan just above the flame. You want as much heat going into that pan as you possibly can manage!