Need Advice: Should I Start Collecting Death Guard or World Eaters?

Hey fellow Warhammer 40k fans! I’m at a crossroads in choosing my next army, and I’d love to get some input.

I currently play Tau (fast, shooty, but squishy) and have previously played Tyranids (a mix of everything). I also own the Chaos Space Marines Combat Patrol, the Battleforce with the Daemon Prince, and 6 War Dogs. I’m interested in starting a dedicated Legion for my next army, and I’m torn between Death Guard and World Eaters.

For those who chose one of these Legions, what made you pick it? What are the main pros and cons of each? How do they each play on the tabletop? What’s the most amazing part of their lore? Also, what’s the best way to start either army?

Thanks in advance for the advice!