Personally, I'd go with what I'm familiar with and can support. If you're better in AWS, that's probably your best bet.
I would also be very cautious about moving your friend to the cloud if they're not ready for it. Will they be able to support themselves after the move? Further, what do their in-house tech people know about the cloud? Anything? Nothing? Do they have experience in Azure, but not AWS? Then Azure might take precedence.
Further, you should evaluate what your friend needs in terms of tech. Broad strokes, AWS & Azure are kind of the same. However, the devil is always in the details. What kind of backup & recovery do you want/need? Availability? Up-time? Tuning? Monitoring? Alerts? Azure & AWS have some VERY different offerings when you stack it all up. So you should evaluate which is better for your friend, not simply convenient for you, based on your knowledge & skills.