Best blow jobs coming to my mind right now -
http://www.mangago.zone/read-manga/follow/ (playing with balls - 1 of my guilty pleasures)
http://www.mangago.zone/read-manga/razoku_no_hanayome/ (seme kisses the uke's d!ck after giving him a head - UBER CUTENESS!!)
http://www.mangago.zone/read-manga/kimi_de_oboreta_ato_wa/ (the blow job of ch.2 --> made my ovaries tingle)
I don't pay much attention to hand jobs that much, mostly because they all seem kinda same to me. NO offense to you or any fans of great hand job.
If it goes to hand jobs, well... I have even a special list ε=ε=(ノ≧∇≦)ノ
http://www.mangago.zone/home/mangalist/28516/
I agree with the Saezuru mention! Chapters 15/16 are amaaaaazing.
I also really like the handjob in Honto Yajuu when they're staying with Tomoharu's parents... I think it's cuz they're like 24 years old but acting like teenagers and Tomoharu looks at Aki's face the whole time. I've obviously thought about this extensively...
Whats' the best hand job or blow job you've ever seen?? In a yaoi manga of course.