PHP is underrated? what year is it? 1990. Well, PHP has dramtically eveloved since rasmus leodorf wrote it for his "personal home pages".
You just cant negelect the power, scalalibilty, performance, huge community of fantastic people who are there for you always. And then, there are people like taylor otwell and jeffery way. Once you get in to test the waters with php, you will instantly fall in love with it. The only answer i have is, to ignore people who say "PHP is underrated".