Smarty is still around and well supported, but Twig is the top choice these days. Symfony is the 2nd most used "framework" these days, Twig is part of Symfony; then on top of that Symfony is really just a set of components (that work hard to adhere to current PSRs) so even projects that aren't Symfony projects will usually incorporate Symfony components as best of breed. Even Laravel relies on Symfony components.