You may be fortunate, in that you have received more than one offer. While this is very nice situation, it can also be a very difficult one. There are several factors to consider when making the decision about the company for which you will work.
Salary is just one of the factors to consider.
You should acknowledge all offers that you receive in writing. Thank the employer for the interest shown in you. Indicate your understanding of the terms for employment i.e. salary, job title, duties, etc. State whether you are still interested in the position. Give some idea as to when you expect to make a decision.