Tara Brach is, without a doubt, my favourite meditation teacher. She has a beautiful way of speaking to the internal experience of meditation, free from a whole lot of New Age stuff... just how it feels to be truly present.
She has a huge range of guided meditations of a multitude of lengths to listen to and download for free at her website. Check them out
Note: I'm not affiliated with Tara in any way. Just a fan!