use strict;
use warnings;
use feature qw/say/;

my %results;

while (<DATA>) {
	my ($id, $string) = (split /[,\s]+/)[0,1];
	next if defined $results{$id} and length $string > length $results{$id};
	$results{$id} = $string;
}
say "$_ $results{$_}" for sort keys %results;

__DATA__
A, texttexttext, col3, col4,
B, textt,        col3, col4,
A, text,         col3, col4,
B, texttex,      col3, col4,

##</code><code>##

# ...
while (<DATA>) {
	my ($id, $string) = (split /[,\s]+/)[0,1];
	my $cur_len = length $string;
	next if defined $results{$id} and $cur_len > $results{$id}{len};
	$results{$id} = { str => $string, len => $cur_len };
}
say "$_ $results{$_}{str}" for sort keys %results;
#...