You can use FireFox and set your default search engine to Ecosia’s. Best of both world’s.
There is also a FF extension called Search For Trees that defaults to Google’s search engine instead of Ecosia/Bing where you don’t have to pre-load each search with #g, unlike Ecosia. The Google search in this extension is a little wacky though so not perfect. Search For Trees donates to Trees For the Future btw.