Hi Zach,
Buying companies in the midst of being bought out is always a challenge. The risk is that if you buy SHAW and the deal falls through, it can fall to pre-bid levels (~24) and the upside is capped at the buy price ($40.50) per share. So, one will have to weigh the risk to rewards and the likely hood of the deal passing.
It is likely that this deal will be highly scrutinized by regulators and and the fact it is trading at a discount to the buyout price means the market is pricing in a risk that the deal won't go through. Doesn't mean it won't, but the market is pricing some risk into it.
If you are looking for the safer play - than Rogers would be the safer of the two as it doesn't have nearly the same downside if the deal doesn't close. So really it depends on your risk tolerance, and whether or not you think the deal will close. I'm about 50/50 on that right now.
Mat