"me too" or "I too"
 

For example,

A: I miss you.
B: I too

A: I miss you.
B: Me too.

Which one sounds better?

Re: "me too" or "I too"
 

The second is correct. Although it's not completely logical, we use object pronouns in this context. Another example :

A : I know John was there. What about David?
B: Yes, him too.

Of course, if the full sentence is repeated, or even just the verb, the normal forms are used:

A : I miss you.
B: Yes, I miss you too.

A : I know John was there. What about David?
B : Yes, he was there too or Yes, he was too.

Re: "me too" or "I too"
 

i agree with susan53

Re: "me too" or "I too"
 

me too :-)

Re: "me too" or "I too"
 

thanks..so..much...

Re: "me too" or "I too"
 

I agree with what Susan said. I just want to add that when you say "Me, too.", you are reiterating the same is true for me, but literally.

For me, if you say:
It sounds like B is saying "I miss me, too." B misses himself.

For me, it would only be natural to rephrase the sentence
A: I miss you.
B: I miss you, too.
(Like Susan said.)

The point is you are in agreement with what was said, not necessarily the idea. Does that make sense?

A: I want pizza.
B: Me, too. (I want pizza, too.)

A: I like Kenny.
B: Me, too. (I like Kenny, too.)

A: I love you.
B: Me, too. (I love me, too.)

Re: "me too" or "I too"
 

Yes - logically Mark is absolutely right, but people do use "me too" to mean I'll say the same about you. Mark, if you say to your wife I love you and she replies Me too - do you really understand that she loves herself? (And I very much hope you don't destroy the moment with a lecture on grammatical logic!) :)

A funny story - I had an aunt who said "me too" all the time. At one point there was a whole tribe of kids between 0 and 3 in the family, and she was chief babysitter. She said it so often that one of them interpreted it as being her name and started referring to her as Me too. It stuck, and the whole family called her Me too from then on.