These are the two most recent Thor series, and they both make great starting points depending on what you're looking for.
God of Thunder is everything you could want from a classic Thor comic. The art by Esad Ribic and stories by Jason Aaron are both fitting of an epic figure of lore, and the series has already solidified itself as a classic.
Goddess of Thunder directly follows God of Thunder. As you can tell, it's not the most traditional Thor story. The vibrant and incredible colors by Matt Wilson are a highlight of the series, perfect for a world of suns and rainbow bridges. This series has it's own beautiful moments, so it's great if you're looking for something different, or want a starting point closer to the current.
The current Thor series and the return of the Odinson. You won't have a lot to read (yet) starting here, but it's a good starting point for catching up to present quickly.