I think it's important to keep in mind here that Berger is really only talking about the potential for TI and Atmel's stocks to move up. He says clearly that his firm is not bearish on TI, but just thinks that Atmel has more upside right now. Just taking a rough look at the numbers, as of the day the article was published, TI's stock was valued at about 72 percent of Berger's target price, while Atmel's was only about 53 percent of his target price. Assuming that the target price is a good, reachable value for each stock, Atmel obviously has more room to move.
In terms of revenues, we are comparing chalk and cheese here. Atmel's revenues are ~$1.6Bn while TI's are in $14bn region. That said Atmel are very strong in the microcontroller segment. Their business focus and strength in a fast growing market (mobile devices) as well as their sound cash flow mean they are a more attractive investment opportunity than a big company like TI which has been through a costly acquisition. This is a no brainer. That does not mean however that TI prospects are bleak in the long term. As Patk0317 above said, TI has the one-stop-shop advantage.
Being an Atmel employee I have to comment on this one. We have products that TI (and others) have tried to copy for some time and given up on, leaving us as the sole supplier. It is not given, that big companies like TI have the necessary skills or knowledge in every team to make market leading products.
Don't ask me about details as I naturally cannot say more.