Polarr

There are plenty of effects apps out there. But clever filters can only take you so far. To get the most from your photos, you need a full on editor. Like Polarr. Yes, it includes some filter-like presets, as well as the typical exposure, contrast, highlight, and shadow controls. But it also gives you access to HSL channels, tone curves, chromatic shift tools, and other pro-level features. Find a look you like? Just save it as a custom preset, and it'll be waiting for you next time, like your own built-in filter. Now that's clever.