If you want to first learn the fundamentals, PHP/MySQL is a good place to start. If you want to just jump in and make something frameworks such as Django and Rails make a nice level of abstraction above the database and even above the raw HTML. If you're looking for a recommendation, I love Django.
My brother was a hacker in the late 90s, early 00s. He has a massive online hockey pool that he created somewhere around 98 or 99, all wrote in php. He wants to revamp the site, which he hasn't fundamentally changed in 5 years or more, and asked me what to suggest. 'python manage.py inspectdb', the built in admin, and clean separation between code and style converted him to Django.
Look and feel? No need to switch from PHP. Performance? A framework might help, but it might not. Maintenance time? Could be looking ground up here.
Again, if this is a redesign for the sake of redesigning, it doesn't really matter what you use. If there is a specific goal though, changing frameworks/languages should only be done if it provides a way to reach the goal.