"Me alegro de verte" is the correct one, but "Me alegró verte" is like you are saying it in past, like you are texting that person after you saw him/her or when you are saying bye to him/her. So both are well-spoken, but it depends on when you want to say. I hope I've helped.

It is always "Me alegro de verte" or "Me alegro de verte de nuevo." If you use that reflexive form "alegrarse" you must use the preposition "de" You can also say "Me alegra verte." which does not require the preposition "De" because it is not reflexive in that case. It means the same thing basically.