What's the best tool to easily collaborate and deliver work (marketing documents) with clients?

You can create documents and easily collaborate on it through comments. It also has the added advantage of being really really easy to use and a beautiful UI. Simple and elegant can't even begin to describe Paper

Simple UI that anyone can use easily. Pair it with Google Drive and Sheets, there is almost nothing you can't do / share!

Yep, I agree! If it's just documents, then I would definitely go for Google Docs. Combined with Asana or Trello if it needs more discussion than just comments on the doc.

If you're doing visual designs, I'd highly recommend something like this. Otherwise if it's purely text, why not go with Google Docs?

This really depends on your deliverables if it's visual you might want something different but if it's marketing projects and the funnel breakdowns Asana has nice reporting features.

Share docuements and collaborate. Awesome tool

Simple and awesome product for collaborating.

Great for collaborating with the team. There's Channels for discussions and meetings. The latter can be taken to a video conference too using the video call/conf feature. What should be of great help is the Google Drive integration if you're using google docs for content collaboration. If not you should be! Flock deeply integrates with G Drive and a lot other external tools. You can also manage your team's tasks, set reminders and stuff... Oh and getting the clients on board part, you can create teams for every client (that'll create mutually exclusive spaces for each client). All your work can be shared here for review and delivery. It also supports file sharing (any format), so your design files too are taken care of. Hope this helps! :)

Super helpful for visual content, the annotation and real time calling capabilities make it super easy to get client feedback.

My team uses it daily and we love it! It has made staying in touch, sharing files, and managing project seamless and easy to do.

There's some great recommendations above - we tend to go with Google Drive for collaboration, but for when you're looking for honest opinion from a client, I'd recommend doopoll. With thousands of customers globally now, we regularly have people praise us over the likes of SurveyMonkey for the simplicity of our platform and the speed of our live results offering. Available, in full, in English, Spanish, French and Welsh.