You have several options, and it really boils down to what you're comfortable with. A few of them, in no particular order.
#1 - Open a new card to transfer the interest-bearing balances to, and make the most of paying that balance off within the window (remember, if you don't do it in the time allotted, you'll pay interest retroactive to day 1, so there would be no benefit to having transferred them). The downside is that you'll get hit initially on your credit score because of a new credit inquiry, and new revolving credit. But in the long run, it will go back up when you pay down the balance.
#2 - Pay down the highest interest balance first, also focusing on paying off the one currently not accruing interest (so you don't lose that benefit by not paying it off in time). This will be most efficient in the long run.
#3 - Pay down the smallest balance first, again also focusing on that balance not accruing interest. This will be the most motivating, if you need to just see those balances going away, though you may end up paying more in interest when all is said and done.
#4 - Pay down the account not accruing interest first and foremost, so you do not lose that no interest benefit, then focus on the other two. Again, you may end up paying a bit more interest on the other two in the long run, but this ensures you don't end up paying on all three. Then you can decide which other balance to focus on afterward.
While doing this, be certain to pay at least minimum due on all three cards, so you don't get dinged for late payments, etc. Another suggestion I always make is to round up payments. It's easier when keeping your records, and every extra dollar put toward that balance means less interest paid in the end.
Lastly, I would NOT consider getting a loan to consolidate, as it will be another hit on you for a new inquiry and new debt. But also because in the credit scoring calculations, personal loans often hurt more than revolving credit already in place. If you can just keep going where you are now, you will be golden!