K - I'm currently running in the black Nike Flyknit Lunar 2 and absolutely love them. Unlike the purple Asics GT 2000s I used to have, they're light but still provide support and stability. Asics are great for support and incredibly comfortable, but I'm not a fan of how bulky they feel when I run. I also love the simplicity and look of the Nike's. The Nike Flyknit Lunar 2 are the updated version of the white and pink Nike Lunar Glide 5. I'd recommend both!
M - The Brooks Glycerin 11 are a great option for anyone with high arches. They also provide a lot of support without being too bulky. The Asics GEL-Lyte33 were my first pair of Asics and, unlike most from this brand, are super lightweight and really comfortable. Once I started to run long distances, I noticed these shoes were better for less intense workouts like cross training. I switched to the Asics GEL-Nimbus 15 which are much more supportive, and overall a really great running shoe. I've learned that in order to be a "runner", I need to get over how cute the shoe is and pick shoes that are designed for my specific needs. This website from Runners World is a really great tool that I used to help me find the right type of shoe I needed.