Ive always had fairly large loads, something i think is party due to simple hydration, i usually drink 6 bottles of water/gatorade a day or more.
As for best reaction it came from a FWB that i had an affair with, we had had sex countless times but i always wore a condom and although she gave some of the best blowjobs ever she never let me finish in her mouth it was always just part of the build up, she said the few guys who had cum in her mouth tasted so bad it ruined it for her yet she still enjoyed sucking cock. When she got divorced she went into a bit of a slut phase, she stopped by my place one day dressed up more so than normal, i was horny tried to get something going but she kept turning me down saying she had a date that she planned on hooking up with and she wasn't a slut that would fuck two guys in one night [yea...sure] , we ended up making out a bit, i slipped her pants off and ended up getting her off through oral, by that point i was rock hard, i tried getting a quickie out of her but again she turned me down but she felt bad since i had gotten her off she didnt want to leave me with blue balls so she offered a blowjob, i said "but you wont let me finish" she smiled and said i could that time saying she had let a couple dates do so recently and they werent as bad as the previous experiences. So i sat back and she started doing her thing, took a little under ten minutes when i warned her i was close, she just picked up her pace [one thing i had noticed over the years though is my loads are even larger if they were caused by a blowjob, i dont know why but thats just how it is] when i couldnt hold it anymore i came hard, like i even surprised myself, she jumped a little but kept sucking and stroking and i just kept cumming, again even i was shocked with how long it lasted, she finally pulled back careful not to let any spill out, she had a surprised look on her face then gulped it back and gasped for air then blurted out "Holy fuck you cum a lot!" she claimed she'd never had a guy who could cum that much [something she claims is still true to this day, several years later] she said she didn't even intend to swallow it but there was so much, had no where to spit and it actually didnt taste bad.
Got even funnier the next day though when she told me i ruined her date, she was worried about kissing him in case he could smell or taste the cum, then on top of that she didnt even get laid cause she was going to give him road head but he blew his load almost as soon as she got his pants open, she gave it a few strokes and that was it, then he couldn't get hard the rest of the night.