I have both setups and frankly they both work well. I would generally go with panniers/racks because I try to carry as little as possible and two rear panniers are easier to deal with than a trailer. But, if I need to carry a ton of stuff my Bob trailer hauls heavy loads well.
The reality is that which solution will work for you is highly dependent on you, your bike and your load. If you have the possibility of trying some of the gear you are interested in before buying that would be a smart idea.