In the past I have gone for Kosher certified meat if I had a choice. I did this not because I was Jewish because I am not really religious at all. I went for Kosher meat and other foods because that usually means the meat or food has an extra level of care and quality control. This means that Kosher foods are usually higher in quality than the roughly equivalent non-Kosher foods. Being a chef and having gone to chef school has really taught me that the quality of the ingredients is the basis for the quality of the food you make out of those ingredients. I also tend to get all natural or certified organic foods as well as Kosher because they all typically have higher quality. I am also a proponent of animal rights and the humane slaughter of animals. I try to avoid meat that hasn't been slaughtered humanely, which is possible as some companies do a very good job of making sure their animals are treated humanely. As with the rest of my food I would get primarily organic or all natural meat. I would also get Kosher when possible because I know the animals are usually treated better too.
That being said I am never going to get Kosher or Halal meat again if I can help it. It turns out that in order for the meat to be Kosher or Halal the animal being slaughtered has to be aware and conscious when they slit it's throat. This means that the animal is awake and conscious and thrashing around in agony while it slowly bleeds to death and/or suffocates on it's own blood.
US federal law requires an animal to be rendered insensible to pain before being slaughtered via various means that are instantaneous (electrical shock, gunshot to the head, physical blow, etc.). This is gruesome but tries to make sure that the animals do not know what is happening to them. But the law specifically provides an exemption for Jewish faith or any other religious faith to slaughter animals as proscribed by the Kosher requirements for slaughter called Shechita. Despite what proponents of Shechita say the animals slaughtered this way do not instantly die. Instead they writhe around in pain for the required time it takes for them to lose consciousness due to blood loss or asphyxiation, which can take several minutes. There are a few countries around the world who ban Kosher meat on the grounds of it being inhumane.
I found this out from the following article and then did some research of my own. I would recommend you search around for info as well if you care about the humane treatment of animals.
http://www.independent.co.uk/opinion/commentators/johann-hari/johann-hari-the-religious-excuse-for-barbarity-2137927.html