The best wheel spacers are properly fit wheels. If you’re settling for spacers and going for flush, 1” all around with rear camber at -.5° is flush with the factory 21’s but you’ll need to trim the factory studs for clearance on the back side of the wheel. If you don’t want to trim, 30mm Eibach spacers are the next best option, use the same rear camber number.
Anyone telling you you need staggered spacers or 1.25” or bigger spacers is just selling you a half measure.