Rack Pack to Strap It Like It's Hot bra. The bra band elastic on the Rack Pack is nearly as wide as the Strap It. I think the Rack Pack also comes up a tad higher in the armpit. The fit on the Rack Pack is a little more relaxed than the Strap It Like It's Hot.
Rack Pack vs. an Energy Bra. The bra band elastic is wider than the Energy bra and the front coverage is higher.
Rack Pack vs. All Sport Bra. The Rack Pack has more front coverage, much better armpit coverage, and a wider bra band elastic.
I don't have a Stuff Your Bra to compare it to but here are photos on the same lululemon model:
Stuff Your Bra on top and Rack Pack on the bottom. The bra band elastic is wider on the Rack Pack.