The Ceres chiller is the best. It only needs ice to keep cold and you can get that anywhere! From what I understand the other brands have ice molds that need to be frozen. That creates more hassle for me as a momma since I would need to re freeze those specific pieces every time and what if I forget? Then I don't have a chiller until they're frozen. I used my ceres yesterday and took it out of the diaper bag today, over 24 hours later and there's still full chunks of ice. Plus they have a new glass bottle insert that is awesome, but it comes with the standard stainless insert. I got a personalized one in Mombre color (so pretty) on sale last month for 25% off which ended up being cheaper than Amazon for a custom one! You can use it so many ways and I've even just pumped in the car and bagged my milk like normal and it fits in the chillers wide mouth no problem and didn't have any issues.
I would highly recommend Ceres, and the customer service is awesome. If you already have an off brand chiller they will send you theirs for free for exchanging yours to them! Check them out seriously I'm so happy with mine, aand they sell adapters and such so you can use it as a water bottle or adult beverage cooler as well so it isn't a unitasker. LOVE IT!