Since PointsHound has unfortunately discontinued their relationship with United Airlines you will need an alternate method if you really need United miles and aren’t happy with any of PointsHound’s other partners.
For people living in the USA, the best current option is Ultimate Rewards. Hotels.com offers a bonus 3 points per $ when you click through their link. Ultimate Rewards transfer to United and other partners at 1:1. For example if you book a lodge that costs $150 a night, you will get 450 bonus Ultimate Rewards points on top of whatever credit card multipliers such as 2x for the Chase Sapphire Preferred. (Sorry folks, don’t have an affiliate link).