Our first choice is to receive the original documents from you, which will be returned, as required by the IRS. Many items, such as brokerage 1099's can be downloaded from your brokerage website as PDF files. These often contain revisions that happened after the paper versions were mailed. If this isn't practical, perhaps due to distance, you can scan your paperwork.
We scan everything we receive. Emailed photos create problems with our scanning workflow, adding extra cost and the potential for errors. These apps will save your paperwork as a PDF which works better than image files.
Just scan everything you have into one or two big PDF documents instead of a making lot of little files that are hard to keep track of. We'll put it all together.
Evernote offers their Scannable app. This is another excellent choice if you are an iPhone user (There is no Android version). It's a natural choice if you use Evernote, although this isn't required. Evernote has a strong privacy policy.
Another fine choice is ABBYY FineReader for iOS and Android. This has a larger feature set than the Genius app, at a higher cost of $5.99 per month or $20/year. You may find that the extra features are worth the extra cost and slightly more complex operation.
Adobe Scan is the most feature rich scanning app on the market. It is a good choice if you are using the Adobe document cloud and Acrobat. The extra capabilities make it more complicated to use than the other options, especially if you don't buy an Adobe cloud subscription.
Dropbox Mobile App has a built in scanner that works very well. One nice option is that you can scan directly to your Dropbox account and share the folder with us. They also have a new standalone scanning app for iOS only. Dropbox has great security and privacy policies.
Cam Scanner by INTSIG is one of the most capable, and probably the most popular phone scanner. The Shanghai based developer is subject to the laws of the PRC. Please read and consider the privacy policy before selecting this app.
Apple Notes has a built in scanner which is not recommended because it cannot make proper multipage PDF's.