Thank you so much.
Thanks a lot.
I can't thank you enough for this.
I don't know how I can thank you.
I really appreciate this.
A: Thanks. That was really nice of you.
B: No problem, happy to help.
A: Thanks a lot.
B: You're welcome, I'm glad you like it.
A: I don't know how I can thank you for this.
B: That's ok. Don't mention it.
A: I really appreciate this.
B: It's nothing.
A: I really want to thank you for all of your help.
B: It was nothing, really. I'm sure you would have done the same for me.
A: Still, you took a lot of time out of your day to help me with this presentation. You didn't have to do that.
B: Yeah, but when I first started here, you went out of your way to make me feel welcome. I really appreciate that.
go out of one's way表示“竭尽全力”
A: Well, I'm glad we could help each other out.