I've written a few weeks ago on this topic. I definitely cum more quickly while masturbating.
Now, if my wife is involved either masturbating me or sucking me, the last a LOT longer. I rarely cum in her mouth from a blowjob as she laid down the law early in our marriage. But she will spend up to 30 minutes sucking and teasing me which is fantastic. Funny thing is, I know she gets precum in her mouth so that must taste fine to her.
If she's giving me a handjob, that will typically last 30 minutes or more. She's very attentive and playful and I'll often ask her to play "rough" - slapping, pulling, or squeezing my balls. She'll often add lube to the job which not only enhances the feeling for me but also helps me last longer.
In both cases - whether she is giving me a handy or blowing me - I'll usually get tot the point where I can no longer stand it and just HAVE to finish by fucking her.