I like DuckDuckGo due to the special search actions that can be performed(especially !bangs), and general layout. I'm also happy with the results. StartPage gives pure Google results, so it might be better if you prefer Google, but don't want tracking.
I have all my search going through https. That encrypts your search to the provider, and prevents a man in the middle attack. Overkill perhaps, but I like the security. I wish the whole web were encrypted. I'd trade the slight speed reduction for security every time.