For me Olympic is hard with its very longs par4 & the fact if you land a small yrd in rough you get 50% lie each time.
Oakmond is also very difficult, bigs elevation & wind not easy to manage together.
Easiest Medion Back9, shorts par4, plenty birdies & it's a tricking course to improve your tier because the par is 34 but average is calculate as an other course (means -3 equal -5 in other course)