2 and 3 are equivalent (and I'll bet that 2 is less efficient). 1 is also equivalent as-is. However, if you were to use these constructs as part of a larger regex, then 1 would not always be equivalent.

#!/usr/bin/perl -l
$_ = '<left>no<right>yes';
/<(.*?)>y/s;
print $1;
/<([^>]*)>y/s;
print $1;
__END__
left>no<right
right
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