All the answers above are ok.

All of the above are correct. From the grammar point, all of the sentences omit the object 我. So they should be 我很高兴见到你 (wǒ hěn gāoxìng jiàndào nǐ) 我很高兴认识你 (wǒ hěn gāoxìng rènshì nǐ) or 认识你我很高兴(rènshì nǐ wǒ hěn gāoxìng). As for the last sentence, 认识你 becomes the topic, making an emphasis on the context. I hope my explanation helps! :-)

我个人认为其实差别并不大，可以根据具体环境来选择。

I think above three answer is ok,but we usually say"很高兴见到你“or"很高兴认识你”

all these answers are perfect but they are too formal like you are at interview with someone or business things. if only meet some new friends we just say 你好, that's it, and you guys can start conversations after 你好，very simple and casual.