Canterbury make a really comfortable upper body protection called the flexitop range.
The flexitop only had shoulder protections, but the flexitop+ has protection on the shoulders, sternum, arms and obliques. It's a quality fit, not too bulky, not enough there for players to grab from under your shirt and if you get the right fit you'll feel the benefit. You may find yourself getting hot in it, but that can't be a bad thing wiht some of the conditions i've played in.
I'm not a fan of the Gilbert, RugbyTech, or Kooga.
Kooga sticks out like a sore thumb and it's really easy to grab as your trying to make a break.
And i find both Gilbert and RugbyTech are flimsy feeling. There doesn't seem to be much density to the padding thus making the product redundant.
These are just my personal opinions on products that i am professionally aware of.
I choose Canterbury...