Think it's fair to say that all the Bing metas have the advantage of a huge index and a fairly refined algo, so they have that.
I'm currently working on the algo ATM, meanwhile the index size is on target to hit 8 billion in the next 18 months. Crawl/refresh rate has been stepped up.
Definitely an interesting space, the 'private search engine', and DDG by traffic are leading it by a mile. What's astounding is that DDG aren't crawling anything and they're doing 50 million queries a day. Their bot just crawls favicons.
There was rumbles of Google being forced to share their index (know of at least one person advising a government wrt anti-competition), but IMHO having separate crawls removes any biases in the indexes in the first place.
Would be excellent if there were 3,4,5 search engines all having a share of the market. Think that'd be ideal, most ideal if they had separate crawls/algos.
