PHP is maybe more bogged down than other languages and Symfony is maybe not the best framework but i had not pleasant experience with RoR either. Either way what ever language and framework you choose it's ok. Personally i would not ever use any of those for pretty big web sites excerpt ASP.NET and some other smaller and much more expensive proprietary frameworks.
PHP for "small" project IMO should work just fine.
I Hear a Symfony: Rails vs. the Symfony PHP framework | townx