Maybe it would be better if a bisexual person would answer since they do like both.
Most Helpful Guy
I think it's more stressful for a guy. Men find more variety of women attractive than women finding men attractive. So that right off the bat makes it harder. Second women are a lot harder to convince. Men are generally simpler and have more leniency. Men essentially do all the work initially. Men can like a woman much quicker than a woman.1
Most Helpful Girl
It depends on what you mean.
I have found it's way harder to actually get a woman and harder to keep a woman, too. I could snap my fingers and get a man, but it's tough sledding attracting women because women are far pickier and women also generally don't approach. It's how hard it is to attract a woman in the first place and then how hard it is to keep them interested that makes me feel the worst, like I have to be all of these things I could never be to have a chance at actually having happily ever after with a woman (which is my preference, not men). It just seems like you have to play more games with women and you can't show exactly how interested you are, either, or else they will get bored, use it to gain the upper hand over you (i. e. control, always getting their way and such) or feel like you're smothering/stalking them or whatever.
Still, I hate dating men and would say the actual relationship with a man itself is worse than the actual relationship with a woman--if you're a woman dating a man, anyway... can't speak for men dating men. You can go through a lot of the same things you would with a woman. But what I hate with men is most operate with an "I'm the man, you're the woman, so I'm supposed to do this and you're supposed to do this" way of thinking. It's almost the exact opposite way I feel with women--with women, I find myself thinking I can never be good enough or act the "correct" way with them whereas, with men, I feel like I can have this, that and the other quality, achievement or whatever over him and he will still treat me/speak to me as if he's superior and as if he's entitled to my interest, my falling all over myself to please him, etc, just because he's a man.
I meet men all the time whom I feel it should be clear I'm out of their league, and they still tell me what I could do to be more appealing to THEM (i. e. do more to my hair, wear more makeup, dress differently, cook and clean, etc) and/or repeatedly try to convince me to go out with them or have sex regardless of how little interest I show. When guys do to this me upon first meeting, it lets me know they'd be a million times worse in the relationship. Still, regardless of the approach, it just seems like all guys have this kind of "you're supposed to bend over backwards to please me" mentality because they're men once you're together or just dating. Most women who act anything like this are at least on my level or better; they're not beneath me acting like this.0