what are pros and cons? I cannot find definitive answers by searching the web. Thanks.

A worm gear oscillation design typically feels smoother and are found in higher end models as a rule. They require no special alignment during reassembly unlike some cam designs. I don't feel like it's life or death either way, but the worm gear is a feature I look for to set a model apart from others. 

A worm gear oscillation design typically feels smoother and are found in higher end models as a rule. They require no special alignment during reassembly unlike some cam designs. I don't feel like it's life or death either way, but the worm gear is a feature I look for to set a model apart from others. 

Thank you for your time. I too like the feel of worm gear oscillation better. I don't find worm gears in two of my daiwa spinning reels. 

 

I saw someone mentioned on the web that cam design is simpler and is more durable. I don't know if that is true. 

Cams are simpler as in less parts but no more durable in my experience. Worm gears are my preference but by no means does that imply that other reels are overall inferior.