I'm in the market for this, albeit for different reasons. Perhaps coincidentally, right after Google announced ending their free storage their sync started acting up for me. Even though I'm a _paying_ customer. In that circumstance the usual Google lack of support becomes quite unacceptable.
For me the key feature is partner sharing. My wife and I take lots of baby photos. We see each other's photos as if we took them. This is the critical feature, and there is I think a large market for it. Even the slick ability to browse photos on the phone is nice but non-essential. Sync two people's photos reliably to a common S3 bucket, and even a janky web interface (+API) will suffice to get us to migrate. Convincing just one partner is easy.
For me the key feature is partner sharing. My wife and I take lots of baby photos. We see each other's photos as if we took them. This is the critical feature, and there is I think a large market for it. Even the slick ability to browse photos on the phone is nice but non-essential. Sync two people's photos reliably to a common S3 bucket, and even a janky web interface (+API) will suffice to get us to migrate. Convincing just one partner is easy.