I loved how encompassing Peace Walker was.
I loved how it was truly a tailor-made experience for handheld that comprised a console experience, but truly an amazing handheld experience.
I loved how it let me be both a boss on the battlefield, and be a boss of my soldiers.
I loved how there were many gameplay side-activities that you could sink hours of your time into, just relating to your soldiers, be it Outer Ops or Upgrades.
I loved how simple they were, yet layered with enough strategy that you had to think things through properly.
I loved how the game gave a sense of identity to your soldiers, even though it's just a codename, quip or a single sentence that describes them similar to Valkyria Chronicles.
I loved how the game was a constant presence throughout my experience with it. How I was recruiting soldiers by walking around pinging wifi spots.
I loved the amount of tools and equipment given to the players, allowing you to play around with a lot of different gameplay styles.
I loved how the game's mission structure challenges you to replay them over and over, to get S-rank, or to get certain parts that you need to change your playstyle specifically to get them.
I loved how when I wanted a brisk 5 minutes experience, I could get it. I loved if I wanted to play a hard mission for 30 minutes, I could get it.
I will admit the game has many flaws. Crappy boss fights, some aspects of the story that I disliked, repetitive boring missions, etc. Looking at it from my objective lenses, I would not rank it higher than MGS1,2,3. Even 4.
But I had the most fun with it. It is my favourite MGS game.