I once let the smoke out of a portable table saw while ripping 2-by. The saw was powerful enough and the blade was new. Unfortunately, it was a miter saw blade and its 60 or so teeth had the wrong rake angle for the task at hand.
Since then, I've paid more attention to the blades I put on my tools. Now I make sure to get the best one for the job–whether it's an old, thin-kerf 7-1/4-inch blade for cutting through a roof, or a new $100 Teflon-coated blade for my miter saw.
Stationary table saws: Fairly thick .125-inch kerf combination blades with between 50 and 70 teeth are usually considered best for woodworking. These blades' tooth configuration (three alternate top bevel [ATB] teeth followed by one raker tooth) cuts smoothly across and with the grain. The stiff blade plates prevent flexing and vibration in tough materials, which might occur with thinner-kerfed (.097-inch) blades.
If you're cutting lots of different materials like MDF, melamine, and hardwoods, a triple chip grind might be for you. The teeth on these blades can handle the brutally blade-dulling MDF, then cut through hardwood without a hiccup. The trade-off might be some cut speed, but you gain a smoother, more effortless cut without a blade change.
Chop and sliding mitersaws: Chop saws and sliders use the same blade design. Most people use -- and most manufacturers suggest –an ATB tooth configuration. More teeth (80 to 90-plus) typically means a smoother, cleaner cut, especially in hardwood and synthetic moldings. For a blade that'll really help prevent tear-out, try one with raker teeth. The raker teeth help clean the cut out so the ATB teeth cut better. Expect to pay around $100 for blades like these.
For fine work, use a thick blade plate (.110-inch) on your miter saw. Less expensive thin-kerf blades can deflect in big pieces of trim, especially when you're just trying to shave a hair off. Teflon-coated blades significantly limit the amount of pitch that builds up on your blade plate and teeth over time. Use the 40-tooth thin-kerf blades for your framing jobs.
Circ saws: There are really two schools of thought here: use-and-destroy or use-and-maintain. The use-and-destroy school recommends buying a lot of thin-kerf blades (.059-inch) cheap and throwing them out when they get dull. When they're new and sharp, they cut fast. If you hit a few nails, though, that's it. At less than $10 a piece, that's not a big deal.
Other carpenters think a thicker-kerf blade (.091-inch) that you can maintain is the right choice. The thicker blades have bigger carbide teeth; they hold up to nails better and you can re-sharpen them to keep them in your fleet longer. However, you'll pay more for them–upwards of $25.
If you want straighter cuts and rips or if you're doing any kind of fine work like using a shoot board to cut built-in parts, stay away from thin-kerf blades–especially dull ones. Even sharp thin-kerf blades can deflect and leave you with a lower quality cut than a stiffer, thicker-kerf blade. Many thin-kerf blades have aggressive hook angles (20 degrees or so) for faster cutting, but they can add to tear-out. Combination blades generally have lower hook angles of about 12 degrees and exit the work more cleanly.