Common intermediate level statistics books include, "Introduction to mathematical statistics" by hogg and craig, and "statistical inference" by Casella and Berger. I own the 1st edition of Casella and the 5th edition of Hogg and Craig. Hogg and Craig is perhaps upper level undergrad (so may be classified as intro by some folks), while a quick google search tells me that Casella seems to be used very often for intro grad courses in a variety of departments (math, statistics, economics, operations research, etc). I'm not sure that necessarily means it is one of the better textbooks...
I personally like Hogg and Craig much better, as it seems to have better discussion to motivate why you are doing what you are doing. Also, at least the 1st edition of Casella is essentially univariate only when it comes to estimation, bounds, etc., which is quite limiting. They are both reasonable books, but neither of them are anything special so i would only buy inexpensive used copies of old editions if you are looking to buy. Check out of a library if you can! I would hope true statisticians would jump in here to give their advice (I am an engineer that uses a lot of statistics - for engineers I recommend the statistical signal processing books by Kay).
The most commonly cited advanced books are those by Lehmann. Not sure how good they are...