Dogtra and Tri-Tronics far and away manufacture the best collars on the market.
I tried some Sportdog collars several years ago and had poor results. The stimulation was inconsistant at best. The customer service was very good, they replaced the collars immediately, but the process was repeated enough times that it got tiring. Sportdog has some good people behind them, hopefully they'll get their issues resolved.
I have used both Dogtra and Tri-Tronics and have been pleased with the quality and service that both companies offer. I prefer the Dogtra collars primarily due to the remote. The Tri-Tronics cylinder remote is great for training but I'm not fond of it for hunting. The smaller Dogtra remote is great for hunting and still works well for training. I found that the larger cylinder type remotes were never with me when hunting, not available for a correction when I needed it. They were on the blind floor, on the shelf in the pit blind, ect, ect - not where I could access it easily when I needed it. The smaller remote clips to my wader/bibs straps and is out of the way untill I need it and then it's handy.
I prefer to have one collar, the one that I works the best for me is the Dogtra 3500. I just don't see the sense of having one collar to hunt with and one to train with.