I was in your shoes a year ago. I chose to live near my reserve job but then again my commute wasn't all that bad to my airline job. Now, I've moved to a different airline and now the commute is more painful so I'm exploring my options again. Here are the pros and cons for each that I can think of:
Living at your reserve base:
For me, the benefit of living where my reserve job is that even when I'm doing reserves I sleep in my own bed. We fly local flights for the most part so I have that luxury. For other units it may not matter. The way I look at it is when I'm doing my airline job I am definitely going to be away from my family if I live at my airline base or not. If I live at my airline base and commute to my reserve job then those reserve days are more nights away from my own bed.
Something else to think about is how often you will drill. On regional pay you will need to drill as much as you can to make up for the crappy pay for the first year. If you are going to drill a lot then you may want to be close to your unit. Also, if you have the opportunity to pick up extra flying on a daily basis at your reserve unit there are great benefits to living near your reserve base.
Living at your airline base:
Now, if you are going to be sitting reserve for a while then there are huge benefits in living at your airline base. Spending time with the family instead of sitting in a smelly crash pad is much better. Plus, you don't have to fork over the extra cash every month for the pad. On regional pay a crash pad is a huge dent in the pocket book.
One other thing to consider is the flexibility of getting home when living at your airline base. Nothing is worse than getting done with your trip only to find that all of the flights home are packed. If you live near your airline base then you know you are getting home when your trip is done. No commute in the day before or waiting until the day after. That equates to more time at home.
Whatever you do, be ready to live where you finally decide to end up until you are done with the regionals. Moving is costly and there is a good chance you simply will not be able to afford to move unless you are there long enough to upgrade.
Good luck in your decision.