Your heart is the most important muscle. If your heart is bad or weak you won't be able to do much else. Humans have evolved for endurance and also to be able to move fast and be explosive if the situation calls for it. To be fast you need to train fast. Personally I prioritize endurance, cardio and speed / explosiveness. Strength training is just a supplement to maintain some basic strength and muscle function. I am not looking to break PRs in weightlifting or look like Mr Olympia.