From the female side:
(based on BB cast standards... really all the casts are pretty attractive)
BB2 - Honestly not much
BB4 - Michelle was really attractive
BB6 - Eh Janelle was pretty attractive
BB8 - Carol was lowkey hot, Dani & Jessica also cute/hot, and Jen was very hot as well - a big contender so far
BB9 - A bunch were kinda cute but eh
BB10 - April hell yes, the rest nah
BB11 - Laura pretty good looking, Jordan & Natalie cute but overall eh
BB12 - A few were kinda cute (Annie/Britney/Kristen) but a pass on all for me
BB13 - Cassi HOT, Porsche/Jordan/Dani all cute - BB8 still beats it but maybe 2nd place
BB14 - Ashley/Danielle/JoJo/Kara/Britney/Janelle are all attractive girls but none really did it for me
BB15 - Kaitlin & Aaryn were very hot ngl, Jessie was cute, GM can look good & Candice was pretty attractive as well
BB16 - Nah not super attractive this season but a hand full of cuties
BB17 - The Nolan twins were pretty good, a couple others were ok but overall eh
BB18 - Natalie was very attractive and Tiff lowkey kinda was too
BB19 - Jessica was damn fine but not much else for me, lowkey (or highkey) found Jillian so hot because of her personality lmao
BB20 - A lot are looking good; Angela, Haleigh, Rachel in particular
has potential
Conclusion: BB8 > BB15 > BB13