What are the best hosting services?
That's kind of a vague question.
When I had to change web hosts because of issues, I always went to http://www.webhostingtalk.com and looked for various comments about the web hosting companies. Expect to spend a few hours reading in there.
You can start by searching webhostingtalk for the services that Thorn007 has highlighted in his post, and go from there. Personally I've been using Addaction.net (shared hosting) for nearly six years. That's after going through something like four web hosts in the first five years I had my web site. Great support (only once did I have to wait for an answer) and uptime.
I like amazon s3 for basic requirements, it allows you to start and grow in terms of size, rather than tossing down hundreds a month for a massive box that you might not even get any use from if things flop.
Dreamhost is great to migrate your site to eventually if things work well, Slicehost is another option, which have far better tech support than dream host.
You could always run your own server depending on your needs.
I have a dedicated server (day job) and reseller account (personal stuff) through Hostgator. They have never been anything less then awesome and the pricing is outstanding.
For shared I recommend Webfaction especially for Django based sites.