The martingale is good for a dog that will try to back out of a collar. I'm not a huge fan of the slip ones because a lot of dogs end up just choking themselves with them. The martingale really shouldn't choke, just tighten when they try to back out.
When we were training we used a regular collar for training and got an EZ walk harness for taking walks. They have a clip in the front so if they pull it turns them. That way when we put on the regular collar it was for training and we could still enjoy walks with the EZ walk. She no longer used the EZ walk at all.
Sorry about your loss, I lost my 14 year old last month