I am a sighted person studying to be an Orientation & Mobility Specialist. I am rating these apps as a requirement of a technology seminar I attended.
I uses both Apps at home and in my office. Seeing AI will scan and then read to you a document, barcode, scene, color, person's face, lighting, money, or even a handwritten note. I found Seeing AI to be accurate most of the time, except when reading colors. It could take anywhere from 9 to 45 seconds for the app to process an image before describing it to you. Also, scenery image descriptions were not very detailed. This App could be very useful when shopping (reading a shopping list or scanning product labels) or reading an important document. It can also helpful in locating a light source. It was easy to use but I would not rely on it to identify colors accurately, because colors look very different in different lighting. It would be nice if the processing time for Seeing AI were a little faster, as someone may not want to stand in front of a shelf or display at a store for a full minute to wait and find out what product is in front of them. I like the multiple options at the bottom of the screen to get a more accurate reading of what you are trying to identify.
The TapTapSee App requires VoiceOver to be turned on. TapTapSee will take a picture of what is in front of you and describe it. It does not read documents. It was fairly accurate in identifying animals, shoes, computers, plants, and other simple objects. Its processing time was much faster than Seeing AI, but that is probably because it does not read text to you. A nice feature of both of these apps is that you can share pictures or documents via email or text. The TapTapSee is quicker but not as accurate. I would want it to read signs accurately to me so I would probably use the Seeing AI App.