A:It's so nice of you to help me.B:__________.用my pleasure.还是with my pleasure.为什么?

My pleasure is ok.

My pleasure，习惯用语

My plesure! 都这样说的

my pleasure
with my pleasure 貌似是帮助之前说的吧……

my pleasure.像with my pleasure 经常是用来回答一个人提出的建议之类

with pleasure 或者是my pleasure 表示不客气，乐意效劳的回答。
with my pleasure 是拥有一种愉快的心情。看例句
I have vanquished, I have uprooted, I have destroyed everything in my heart that might have interfered with my pleasure.
我铲平、根除和摧毁了我内心中所有可能削弱我的快乐的因素

My plesure!

my pleasure :不用客气,这是我的荣幸,愿意为你效劳 用于回答别人的道谢
with pleasure ：当然可以,愿意效劳 用于回答别人的请求帮助

都可以，my pleasure 更口语话，跟with my pleasure一个意思

my pleasure 就阔以了~~
像with my pleasure 经常是用来回答一个人提出的建议之类的，比如A说咱下午一起看电影去吧，这时B就阔以说，with my pleasure~~
希望你满意~~