“I’m excited to be a part of your team and I look forward to working with all of you.” 🌈

2 because "be and work" 4 because "am excited and look forward"

#1 implies that you are already working with the team and excited about it. It's a good choice if you're already started working or have been formally introduced to the team. #3 expresses your excitement about joining the team and your anticipation of working with them in the future. It's a good choice if you haven't yet started working or haven't met the team formally. So, If you're already working with the team choose #1. If you haven't started working yet choose #3.