AnyList. I’ve tried many list apps and this one is easily the best. Not FOSS disclaimer. The free version has very minimal ads, it has a great, intuitive UI, you can create custom list types and item categories, it has built in quantity and unit of measure fields, and you can share/sync a list with others by email address. The amount of features included in the free version is uncommon in the market without getting more harassed by advertisements. I hope it doesn’t change in the future; it’s remained relatively unchanged for the 3 years I’ve been using it!