Recommend me a game collection tracking service!

[VGPolyglot]

Conina said:

Do Backloggery, Darkadia or VGCollect have import options for digital libraries?

So you enter your Steam-ID, GOG-name, PSN-name, XBL-name and NNID and all digital purchases get imported automatically and get synced frequentially? Then you only have to input every retail game manually.

For VGCollect, no. I'm not sure about the others.