Gamers will not have a hard time recognizing that these are two different handheld devices that can be used. Two different companies make these. Nintendo created the DSI while PSP created Go. People may have different preferences, depending on which one is better. Some prefer one over the other because of the different games that they offer.
Others favor the Nintendo DSI because it has two screens. Some say that if there is any comparison with what Sony has created, the PSP 3000 may be a better option. A lot of people wanted to have PSPs when this was released at that time.