I played from the release of Onslaught through to Ravnica when I was a little kid
The decline started when I learned how to actually deckbuild through buying singles online instead of frankesteining shitty decks with a bunch of stray cards from packs and trading with my friends. Aesthetics and lore wise I feel like the game was already in decline when I picked it up, Kamigawa was good but Mirrodin and Ravnica were both really lame compared to the older sets that were around when I started playing.
On another note, last I played planeswalkers and the commander format didn't exist, both of those seem like they'd be extremely annoying from what I've seen