There are a lot of liquid yeasts to choose from and in order to keep this simple I will just describe them by general strain. All of the brands of liquid yeast I can think of (Wyeast, White Labs, Yeast Culture Kit Co., Yeast Labs, and Brew-Tek), are of very good quality, and to describe each company offering of a particular strain would be redundant. This is not to say that all of the cultivars of a type are the same; within a strain there will be several cultivars that have different characteristics. You will find that each company's offering will be subtly different due to the conditions under which it was sampled, stored, and grown. You may find that you definitely prefer one company's cultivar over another's. Detailed descriptions of each company's cultivar will be available at your brewshop or on the company's website. This is an incomplete list because new strains are being added to the market all the time.
All Purpose Ale Yeasts
American, Californian, or Chico Ale
A very "clean" tasting yeast, less esters than other types of ale yeast. Good for just about any type of ale. This strain usually derives from that used for Sierra Nevada Pale Ale. Medium attenuation, medium flocculation. Suggested fermentation temperature is 68°F.
This all purpose strain comes from Thos. Cooper & Sons of Adelaide, and produces a very complex, woody, and fruity beer. Medium attenuation, medium flocculation. Great for pale ales, brown ales and porters. Suggested fermentation at 68°F.
This strain comes from Whitbread Brewing Co., and ferments crisp, slightly tart, and fruity. More maltiness is evident than with the American ale yeast. Medium attenuation, medium flocculation. Suggested fermentation temperature is 70°F, though it performs well down to 60°F.
Ale yeast from Wissenschaftliche in Munich. A full bodied complex strain that finishes very malty. Produces a dense rocky head during fermentation. Suggested fermentation at 70°F. High flocculation, low attenuation. It's clean and malty, especially well suited to Altbier. Reportedly a slow starter (longer lag times).
Specialty Ale Yeasts
Lots of fruity esters (banana, spice), and can be tart. Very good for Belgian ales, Dubbels and Tripels. Low flocculation, high attenuation. Suggested fermentation temperature is 70°F.
Ferments dry and crisp leaving a good balance of sweetness and tartness. Produces an extremely rocky head and ferments well down to 55 °F. A good choice for Alt style beers. High flocculation, high attenuation. Suggested fermentation at 62 °F.
The slight residual diacetyl is great for stouts. It is clean, smooth, soft and full bodied. Very nice for any cold-weather ale, at its best in stouts and Scotch ales. Medium flocculation, medium attenuation. Suggested fermentation at 68°F.
An old German style of beer that is more lager-like in character. Nice maltiness without as much fruit character as other ales. Some sulfur notes that disappear with aging. Low flocculation, high attenuation. Suggested fermentation temperature is 60°F.
Complex, woody, tart, with strong mineral notes. Could be from one of the several renowned London breweries. Slight diacetyl. High flocculation, low to medium attenuation. Suggested fermentation temperature is 68°F.
Wheat Beer Yeasts
Belgian Wheat (White) Beer
Mild phenolic character for the classic Belgian White beer style. Tart and fruity. Medium flocculation, high attenuation. Suggested fermentation at 70°F.
Produces the distinctive clove and spice character of wheat beers. The low flocculation of this yeast leaves the beer cloudy (Hefe-Weizen) but it's smooth flavor makes it an integral part of a true unfiltered wheat beer. Low flocculation, medium to high attenuation. Suggested fermentation temperature is 65°F.
A tart, fruity and phenolic strain with earthy undertones. Medium flocculation, high attenuation. Suggested fermentation at 68°F.
Very versatile for most lager styles. Gives a clean malt flavor. Some cultivars have an almost green-apple tartness. Medium flocculation, high attenuation. Primary Fermentation at 50¡F.
Lager yeast strain used by many German breweries. Rich flavor, full bodied, malty and clean. This is an excellent general purpose yeast for Lager brewing. Medium flocculation, medium attenuation. Primary Fermentation at 48°F.
Ferments clean and malty, giving a rich residual maltiness in high gravity pilsners. Very suitable for Vienna and Oktoberfest Styles. Medium flocculation, high attenuation. Primary fermentation at 48 °F. Probably the most popular lager yeast strain.
Warm fermenting bottom cropping strain, ferments well to 62 °F, having some of the fruitiness of an ale while keeping lager characteristics. Malty profile, highly flocculant, clears brilliantly. This is the yeast that is used for Steam - type beers.
Czech Pils Yeast
Classic dry finish with rich maltiness. Good choice for pilsners and bock beers. Sulfur produced during fermentation dissipates with conditioning. Medium flocculation, high attenuation. Primary fermentation at 50°F.
Danish Lager Yeast
Rich, yet crisp and dry. Soft, light profile which accentuates hop characteristics. Low flocculation, medium attenuation. Primary Fermentation at 48°F.
Munich Lager Yeast
One of the first pure yeast strains available to home brewers. Sometimes unstable, but smooth, malty, well rounded and full bodied. Primary fermentation temperature 45 °F. It is reported to be prone to producing diacetyl, and accentuates hop flavor. Medium flocculation, high attenuation.