The @ symbol you get is dependent on the font you use. As you note, the standard Computer Modern @ is quite different from e.g. the one in Times. So you can define your own macro to insert the @ from a different font, and then choose whichever @ you like best.
Here's an example of substituting the Times font itself (with Computer Modern below for comparison). Another reasonable alternative is Charter (
% Computer Modern
Some people may tell you that you shouldn't switch fonts for a single symbol like this, since the relative weights of the fonts look different, (as you can see from the image above) but for most purposes this may not be an issue.
For a list of most of the commonly installed fonts and their internal names see this question:
How do I use a particular font for a small section of text in my document?