Greetings from Switzerland.
I have 2010-era ReSound Dot2 in both ears - these take size 10 batteries.
My audi sells both Rayovac and Power One (Varta) - prices are pretty similar unless he has a special offer on one of them. Locals supermarkets stock both Duracell and Varta branded batteries but I’ve never bought from them as they only sell single 6-packs rather than the more economical boxes of 10x 6-packs.
I get at best 3.5 days with the Rayovacs, and usually nearly 4 days with the Power Ones.
I tended to get a lot of duds with the Rayovacs - maybe 1 in every second 6-pack so, and so after swapping between both brands in the early days based on price, I’ve been using Power Ones exclusively in the past 2-3 years.