Do you already have job offers for all three options? The first thing you should do is to apply to all summer RA positions out on the market (there aren't that many).
When choosing between your offers, I'd say the relevant considerations ranked by importance are:
1) Job content (will you be doing useless grunt work, or is it going to be something interesting?)
2) whether the PI is an active researcher
3) reputation of PI
If the idea is to get a good letter of recommendation through this RA job, the main factor to consider is whether you'll have an opportunity to demonstrate your research potential. The heavenly scenario would be if a professor at your school gave you a really interesting project to work on. Otherwise, I would lean towards the Fed internship. Sure, maybe their reputation isn't as strong as top 10 school economists, but their summer programs are very structured and they have their RA's do interesting stuff. If you're at a top 10 school, you'll have plenty of other opportunities to get good letters: your next RA job, thesis adviser, classes, etc.