FWIW, heredocs aren't ugly :) if text is more than one line, heredocs are my first choice, of the form

my $html = <<'__HTML__';
__HTML__

my $xml = <<'__XML__';
__XML__

my $foo = <<'__EOF__';
__EOF__
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I've often pasted multiline text and had to adjust the delimiters, ditching '' and "" and {} for q~~. With heredocs this is very rare. I've had HERE or EOF show up a few times, but virtually never __EOF__, which I also like for its similarity to __DATA__ and __END__

Its part of my template, I even have a hotkey in my editor for heredocs

I also prefer  qw' l i s t ' or  qw/ l i s t/ because no shift key is involved, and its all pinky action (on QWERTY keyboard),  use CGI 3.55 qw/ param /;  use Data::Dump qw' dd ';

for oneliner portability, i prefer qq// and q//, much easier to move between shells , only have to change leading/trailing "" into '' and vice versa

For match/substitution, i prefer  s/// and then to avoid leaning toothpick syndrome i switch to one of  s;;;  s=== depending on the regex, similarly because shift isn't required, and its all pinky action :)

for larger regex I always use balanced  s{}{}ex; or

 s{
}{
}ex;
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though the options are ridiculous :D

perl -MO=Deparse -e " s///g "
perl -MO=Deparse -e " s\\\g "
perl -MO=Deparse -e " s[][]g "
perl -MO=Deparse -e " s()()g "
perl -MO=Deparse -e " s{}{}g "
perl -MO=Deparse -e " s!!!g "
perl -MO=Deparse -e " s###g "
perl -MO=Deparse -e " s vvvg "
perl -MO=Deparse -e " s ___g "
perl -MO=Deparse -e " s {}//g "
perl -MO=Deparse -e " s {}\\g "
perl -MO=Deparse -e " s {}vvg "
perl -MO=Deparse -e " s {}()g "
perl -MO=Deparse -e " s {}[]g "
perl -MO=Deparse -e " s {}<>g "
perl -MO=Deparse -e " s<><>g "
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you're correct, you definitely want to avoid alphanumeric for delimiters, esp fancy unicode