It depends on two things: What you are going to use if for, and what you are comfortable with.
When I was framing houses many years ago, I used a sidewinder. I liked it a lot. However, some of the guys that came to work or sub from me used the worm drives. I didn't like them, but boy did I respect their power. They could take a blade that I took off my saw and use it for another week to burn the whole blade blue without choking down the saw.
I didn't like the worm drives because they were heavier, and all of them were left bladed, which meant the that saw sat on the piece that was going to fall off. Not a big deal with a wrap around table/shoe, but I like the saw to be on a surface as solid as possible when cutting.
I also couldn't use the worm drive on finish paneling and it was uncomfortable for long rips; I was unable to use my "finger rip guide" as I had to that point without scaring the crap out of myself. Nor was it as easy to use with my shop built rip guides to do finish ripping for cabinet shelves, etc. For ripping soffits, decking, siding, and just about all framing, it kicked ass.
That being said, if you buy a worm drive, you will never need to buy another circular saw in your life just to saw wood. Some may be better than others, but they are all tanks.
If you are going to use the saw around the house for building a deck, repairing fascia, putting in shelves, some light remodeling and for an occasional project, get a sidewinder. I personally didn't like the DeWalts or Porter Cables simply because they have grooved shoes. When trying a compound miter cut (think repairing the >>scribe