how would you filter which one to get first, considering that they all address the same target group, that is beginners to Perl6? would you weight the author's name more? the number of pages? the index? the publisher?
this is where timing gets critical,because if you were looking to get started with perl6 at a a time where just one title was accessible,you wouldn't have to think twice.
but now it gets complicated, for both publisher and potential reader audience.