I'm hearing still no movement from the club on either site yet - but could be as much as 80/20 in favour of Stonebridge vs waterfront in terms of likelihood as it stands. (echo have just published an article suggesting SC more likely too:
http://www.liverpoolecho.co.uk/news/liverpool-news/could-new-everton-stadium-help-11344102)
Bit concern over Waterfront would be travel infrastructure. Whilst we do have a large 'walk up' fan base, there would still be a huge amount of parking required for a 50+k seat stadium, and would lead to massive congestion around the area.
Stonebridge would also require massive parking but there is the space out there to build purpose built parking, and it has good motorway links.
Also the fact that the land is readily available for development and is in Council ownership - and in one of the Mayor's development areas in Stonebridge, so little/no planning permission needed. Whereas Peel own the land on the waterfront so would be a more costly and difficult negotiation.
Sorry to be bearer of "bad" "news"!