Is vacuum sealing a lot better or does using a normal zip close bag work just as good? For zip close, are silicone bags like Stasher better than using a plastic Ziplock? Thanks!
I just use the Ziplock freezer bags. Using the water displacement method works just as well as a vacuum sealer. 
Going from freezer to your sous vide vessel is a breeze when you’ve prepped meats before freezing. Don’t use regular sandwich bags - they’re too thin - very prone to leaking.
Thanks! How do you do the water displacement method?
Immerse the Ziploc bag up to the mostly closed zip without letting any water into the bag and zip it shut. The objective is no air and minimum water. For heat transfer considerations, air is a good heat insulator, water not so good, but plastic transfers heat as well as the piece being cooked.
I prefer to use vacuum bags. I have learned to leave lots of extra room - twice minimum - when vacuum packaging for the freezer. Then when I decide on the recipe and its aromatics / seasonings, I cut the bag open near the seal, add the ingredients, and revacuum reseal.
Not knowing where you are, likely costco uk / u.s. will stock the double ziploc you require, made to withstand sous vide temps, other thin types will burst at low temps around 62c
The 1litre bags “small” are enough for 6 chunky sausages / 2 standard burgers / nice steak
The medium bags are 3 litres …enough for a decent roast, we hardly ever use those to date, just cooked off 1.2kg in 3x small bags (18 uk sausages)
Our preference to vac sealing 95% of the time, quick & easy.
In the uk its “bacofoil brand” …for elsewhere just “ziploc” I guess.
Ziploc bags are best in reccomendation