After the first challenge of selecting the appropriate razor for your wet shaving setup, then the question of which blade comes in to play. With the increased popularity of traditional wet shaving over the past few years, many different brands of double edge razor blades from different parts of the world have become readily available. While most are perfectly capable of performing the basic duty of cutting through hair, there are differences in each blade that have be taken into consideration.
Because every person's skin and hair type is unique, it is very difficult (if not impossible) to recommend one blade over another. A blade that provides a smooth and comfortable shave for one person may be harsh and uncomfortable on someone else's skin. Most people would assume that the sharpest blade possible equals the best shave; however, you will quickly find out this is not always the case. Take into consideration the sensitivity of your skin and your hair coarseness, and it is clear that some trial and error is required in determining which brand of blades works best for you.
If you are making your first purchase of razor blades, it is highly recommended that you buy a small assortment of different brands and see how they work for you. Several retailers have special sampler packs that give you a cost-effective way to explore your options before committing to a large purchase of blades. The DE Multipack from Lee's Razors is a great choice to sample four of the most popular brands. Start with the mildest blades and work your way to the sharpest, as explained in this Q & A: What order should I use my blade sampler pack?
There many other brands and sampler packs available -- many of which are great blades. The following descriptions (listed alphabetically) provide a brief introduction to a range of different brands, so that a beginning shaver can have a reasonable starting point to determine what works best for him.
BIC 
The edge on the BIC Chrome Platinum blade is well known for cutting smoothly while being rather forgiving. BIC blades are sharper than most of the blades in its price category, such as Derby, but do not have the extreme sharpness of Feathers. BIC blades are gentle on the skin and benefit many men who are still learning proper technique or who have irritation problems from blades that are too sharp. The BIC is also a good choice for more aggressive razors, such as the Merkur Slant Bar. These are solid performing blades at an affordable price.
Crystal 
Crystal blades are also sold as Blue Personna, quality blades made in Israel. Crystals are quality sharp blades that are a step down from Feathers, yet offer a smooth shaving experience for men with heavy beards. The edge on the Crystal is noticeably sharper than that of other brands, such as Merkur and Derby, resulting in a smooth shave with no tugging or pulling due to dullness. Crystal blades are a good choice for men of all skin types and beard densities looking for an affordable and well rounded blade that is not too harsh or overly aggressive.
Derby
Derby blades are one of the biggest sellers with shaving retailers and have gained a loyal following. The Derby has a smoother cutting edge than many other blades and works well for men with sensitive skin or that are prone to irritation from blades that are too sharp. While the Derby blades are much smoother, they still have a tendency to be a bit too dull for those with very dense and heavy beard growth. Derby blades are also one of the most inexpensive brands available, making them very attractive to many shavers who are budget conscious. For a beginner wet shaver, Derby blades make a great starting point in determining what works best for you.
Feather
For many shavers, there is nothing comparable to the Feather blade. These Japanese-made blades are the sharpest available on the market today. Feather blades are renowned among wet shavers for their ability to easily cut through even the coarsest beard types with ease. Because Feathers are so sharp, men with very sensitive skin can find these a bit uncomfortable and overly aggressive. The use of these blades also requires that you are proficient in properly preparing your skin and creating a protective lather with your shaving soap or cream. While these are very high quality blades, they are not recommend for beginner shavers as they leave very little margin for error if you are not accustomed to proper pressure and blade angle with your safety razor.
Merkur
Merkur blades are probably the easiest blade to find in retail stores today. Merkur is the largest manufacturer of traditional wet shaving products and can be found virtually anywhere quality shaving goods are sold. Many specialty stores, such as cigar and pipe retailers, carry basic Merkur products. The Merkur blade is a very good starter blade for men with normal skin types and light to medium beards. These blades have a slightly rougher edge to them that can be a bit uncomfortable for men with coarse hair or heavy beards, and often are described as having a bit of "pull" because of that. For many men, though, the Merkur provides a good shave -- and being easily available is a big plus.
Red Personna
Like the Derby, Red Personna blades are also very smooth cutters and appeal widely to men with sensitive to normal skin. The edge on the Personna, while not quite as sharp as other blades, still provides a comfortable shave without any excessive pulling or irritation. The edge on the Personna is very much on par with the Derby, working well for average beards, but still not suitable for men with heavier beard growth. The Personna is also a more inexpensive blade making it a popular option.
Sharp
Sharp Stainless are low-cost blades that are marketed to men with moderate beard growth or with sensitive skin that is prone to irritation from the better blades on the market. Contrary to its name, Sharp blades do not have the edge sharpness found in many other blades, such as Personna, BIC, and Feather, and are not very well suited for men with coarse and heavy beard types. Sharp blades are an inexpensive option appealing to budget-conscious wet shavers. Sharp, Astra Superior Platinum, and Gillette 7 o'Clock double edge blades are similar in price and performance.
Other Brands
When you are shopping around for razor blades from various shaving retailers, you'll see there are many out there and plenty of opinions on what you should buy. Transitioning over from cartridge razors, where you have two primary brands, Schick and Gillette, can make this selection a bit overwhelming at first. The descriptions above address several of the most commonly available brands, but there are many beyond this list. Other common blades are produced by Lord, Dorco, Shark, SuperMax, Wilkinson, and others. Based on your skin type and beard coarseness, try a few different brands of blades to determine what works best for you. With a little time, you'll find the right double edge blade that provides a close and comfortable shave that you can enjoy every day.
= very sharp = very mild
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