A few things worth weighing before you pick one: how good the trend graphs actually are once you've got a few months of data in (a lot of apps look fine on day one and get unreadable once you're tracking 10+ parameters across multiple tanks), whether it handles ICP lab results automatically or you're stuck typing in 30 values by hand every time a Triton/ATI report lands in your inbox, and whether it logs dosing and water changes alongside parameters so you can actually see cause and effect, not just numbers sitting in isolation.
Full disclosure since it's relevant here I'm Christian, founder of ReefDiary (reefdiary.io). I built it because I kept running into exactly this with my own tanks. It logs 30+ parameters with trend charts, and you can upload an ICP report PDF and it'll parse and sync the values into your history automatically instead of you retyping them. There's also an AI chat feature that looks at your actual synced tank data when you ask it something, rather than giving generic advice. Not saying it's the only option worth a look in this thread Aquarium Note 2 and Aquatic Log both clearly have loyal users for good reason just flagging what to compare on.