I currently use PowerTools Filter Menu.
However, the missing ability to use "AND" function is frustrating so, for example, you can't click two brands in the same filter section eg. ZARA "AND" RALPH LAUREN - it won't allow you to display both. It really annoys me how this isn't an option and feel its hindering website usability and conversions.
I've looked at a few apps and the two linked below seem pretty good.
Which would you recommend? Happy to look into other apps too!
I recommend you should try Ultimate search and filter https://apps.shopify.com/ultimate-search-and-filter-1 using AI technology for instant search and product filtering. The app offers advanced features including Autocomplete for search and Dynamic product filtering (filter products by Product attributes and Meta fields), Color and Image Swatch Display, Merge values, Price slider, Product count for filter value, Breadcrumb trail (selected filter values), Multiple selection, Search and Filter by variant where image seamlessly matches with variant selection.
Moreover, you can utilize the power of AI technology in search (Synonym search, Natural language processing), Merchandising to promote your marketing campaigns (promote high-profit margin products, sales products, promotion banners) and Internal site search analytics.
See the demo store for more details: https://usf-vertical.myshopify.com/