First off, I'd like to preface this post by saying that everyone is different and I'm not suggesting that anyone's opinion is wrong. Just writing this to post for people who were in the same situation as me and could benefit. I used to be a huge Apple fan, but the last few years, they lost me. Besides my rMBP, I switched from an iPhone to Android due to iOS's lack of innovation. I traded my regular iPad for an Android tablet (big mistake). So, what I was looking for was something that would be a laptop replacement or at least accomplish 90% of what my laptop could do. I was actually very gung ho on getting the Surface Pro 4 because I thought it would give me the best of both worlds. But since it was the holiday season, Best Buy had the return policy until January, so I bought both to try out to see which one I'd like more. The fact is for me, neither device could completely fulfill what I was looking for. But I definitely went into this expecting to return the iPad. Surface Pro 4: Overall, it's a nice device. Windows 10 is a huge improvement. The issues I had was for me, the trackpad was laggy, the battery life was subpar and it was a better laptop than it was a tablet. There are virtually no good apps and while it obviously runs desktop applications, it really works better when using it like a laptop. I could never get comfortable with it without the keyboard. It's heavier than the iPad Pro, and I didn't feel like it felt very good in my hands as a tablet. When I tried to use it as a laptop, I felt like I wished it were my rMBP. I bought the i5, 256GB version which was $1299 plus the $129 for the cover. So, I was spending $1428 for this package for a device that is not quite a good tablet and not quite the best laptop for that price. iPad Pro: Like most others on the forum, iOS is its biggest limitation, however, as far as a tablet is concerned, the apps are overall excellent and the tablet experience is fleshed out well. It was capable of doing most of the things I needed it to for productivity such as writing/editing Word docs, work on spreadsheets, photo editing and obviously email/web. Is it as good as a desktop version? No. But for me, I don't use the major advanced features often. I don't do video editing at a high level. For costs, I bought the 128GB WiFi model, the keyboard and pencil. So, the whole bundle was around $1200. I personally love the pencil and it's inspired me to draw for the first time in 20 years. Procreate is amazing for sketching and I feel like the tablet experience works very well for a "sketchpad". What I will say is the iPad Pro is clearly a better tablet than a laptop. Conclusion: I returned the Surface Pro 4. The major reason being is that it wasn't very good as a tablet and while it worked better as a laptop, I realized that if I wanted a laptop, I'd rather use a "real" one that is optimized for the things I want to do with a powerful machine. No one will convince me that the SP4 is better than my rMBP. So could I replace my laptop? No. But the iPad Pro does so many things very well for me that I haven't used my laptop since I got it. Another huge benefit for the iPad was its battery life. It was at least 4-5 hours better than the SP4 and it was lighter and I felt more portable. Again, this isn't for everyone. I recognize everyone's needs are different and some may disagree. I'm personally very happy with the iPad Pro and have used it more than any tablet I've used in the past. I don't think it's possible to have a perfect replacement. For me, I wanted something with great battery life, could handle my modest productivity needs and my consumption usage. I've been able to use this for web, email, drawing, document creation, spreadsheet editing, games and video. For me, that's all I need. Hope this was helpful for anyone debating between the two devices.