I'd go with any 4-piston brake that's cheap but isn't the lowest end model. Like a Sram DB8, Codes (stealth or older lever style), Shimano SLX. Usually you can find older, high-end brakes for cheap online, too. Jenson USA has got a lot of options for not that much -
https://www.jensonusa.com/mountain-bike-brake-sets?s=price-asc