so, mine are now 18, 15 and 13. I have loved being a parent. and they have been mostly pretty cool kids.
I think the 'hard' really varies with age.
Of course it also varies with your kids (good/bad sleeper for example) and with what you are like. I loved messing around with cooking and crafts etc when they were younger. I have loved the funny meme sharing they do now and I loved the snuggly baby cuddles too.
Baby and toddler age is relentless, physically tiring. But in a way the demands are fairly simple and straightforward (food, sleep, cuddles). Tantrums may or may not come, but you can pick up a tantruming toddler and walk away with them! But it is the relentlessness of it which does you in, no repsite, that dreadful 6 am MUMMMMYYY.
teenagers are quite different. Not physically demanding at all really, I get lie-ins and days off, and I am not in demand 24/7 but bloody hell the emotional rollercoaster of the teenage years has broken my heart. My kids are actually great, they haven't been 'difficult' teens. But they have needed support with stuff that I don't know where to begin. (trans issues, anxiety etc) and I feel that it is impossible for me to help them.
Honestly? I'd rather have toddlers again. I look with some envy at a friend with her 4 little ones, doing cute easter crafts. The only reason I wouldn't go back is because they grow up, and they will break your heart.
The only relief is that ds, now 18, has suddenly come out fo the end of some of it, and is reflective and helpful about what it was like being a teen today, which has made me see that 1. they do come out of the other end and 2. given me perspective on younger ones.
I love being a parent. But after the last 3 years, I think that given a choice of doing it all again, I might say no.