Breastmilk storage bottles vs disposable bags, which one is easier to use? Any brand to recommend?

I have both. Breastmilk storage bottles are good for storing chilled expressed breast milk which you are intending to feed soon. Mine are from Autumnz, which are very affordable and are compatible with Spectra breast pumps. Medela has milk storage bottles as well. There's also Pur Milksafe Vacuum storage bottles, which comes with a vacuum pump to prolong freshness. Disposable milk bags are good for storing frozen breast milk as some bags are able to be frozen flat (Boots, Lansinoh, Pigeon). I'm using Jaco Perfection milk bags from Korea because of the affordable price (about $25 for 120pcs).