Whether is the more teeth on the saw blade, the better

The more teeth, the smaller each will be, the smaller the chunk removed by each tooth and the cut edge will be smoother. Fewer teeth, bigger chunks and the saw will cut faster with rougher cut edges. The tooth size chosen decides how smooth the cut is. Also, if the cut is cross grain, more teeth makes a smoother cut, cutting along the grain is naturally a bit smoother and larger teeth can be tolerated and the cut will be faster. Plywood, with grain running both ways, is smoother cut with a fine toothed blade, and a hard or knotty grain may need to be cut more slowly.

So, the blade you choose depends on the hardness of the wood, whether you are cutting cross grain or along it (rip sawing), and how smooth an edge and cut you need for the job.

When you buy a power saw, it will usually come with a general purpose blade which generally will do a good job on a wide range of tasks. If you get into serious woodwork, you may wish to buy good quality specialist blades. Saw blade purchase was very fine toothed. It cuts ply like butter and the edge is so smooth it's near unbelievable.