It's really a matter of preference. There are many features of an editor or IDE such as syntax highlighting, code completion, code folding, buffers, tabs, multi-platform ... Each editor or IDE has some or all of these features, and you'll have to decide which features are important to you.
See http://wiki.python.org/moin/PythonEditors for a list of editors, and http://wiki.python.org/moin/IntegratedDevelopmentEnvironments for a list of IDEs.
This question is asked every few weeks on comp.lang.python so searching the archives will yield many opinions.
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