My favorite Weapon Rings are:
Red Ring - Even though it may be a basic weapon, but I like this weapon when I use Knuckles. This ring is great to use against players who are currently protected by an Attraction Shield.
Auto Ring - I like this ring because you can fire rings at a fast rate, but when you use Knuckles, you fire them at an even faster rate. In close corners, this is pretty much unavoidable if the ceiling is lowered and the player can't jump.
Bounce Ring - Boing! I like this item because it can bounce in close corners and even out in open fields.
Grenade Ring - I like this ring due to its proximities. When used, if one or more players land in a ring of these, you'll rack up points quickly.
Weapon Rings I hate:
Scatter Ring - Not only does this ring spread out in 5 directions, but people spam these all over the map! Why is that?
Explosion Ring - The radius of the ring can go through thin floors. (See Meadow Match for example) I also hate the fact that you get knocked back far when hit directly. I'm okay with getting hit with the radius though.
Rail Ring - Oh hell no. This ring is for experts. I rarely get a hit with this ring. When you get hit by it, it's really hard to get your rings and panels back after one hit.