Both can be pretty nasty as far as symptoms go and neither are good for your body. Although in my personal opinion, after seeing my friend with hyperthyroidism loose 25 lbs in a month, vomit after eating anything, have freakish abscess and horrifying blood pressure, have miscarriages and frequent panic attacks. And THEN become anemic because of the medicine they gave her- I'm thankful for my under active thyroid. My road hasn't been easy but from this side of the fence I feel like I can deal with it more than I could if I was in her shoes. Although I'm not going to lie either, before I went onto the thyroid medication I was in a pretty bad place too.
As ducky said, both can produce some pretty horrible symptoms, but if I had to make a choice, I'd rather be a bit hypo than hyper.
Either way, we all have our horror stories.
I have to agree with the posts so far here. My grandmother has graves disease and as a result became hyper thyroid. She almost died due to cardiac complications that were related to being hyperthyroid and in the end had to have her thyroid completely removed. I also have several friends with hoshimotos and when I was recently diagnosed myself I was grateful that I had the thyroid auto immune that causes hypo rather than vs. None of my friends have had the level of issues that my grandmother experienced. I am by no means an expert but based on personal experience and relationships I would have to say it appears hypo is easier and safer to treat.
Speaking from the experience of having both, I would take hypo any day of the week over hyper. I spent a year in hyperland and it was the worst time of my whole life. The bad part is you have lingering effects. If you suffer from the panic attacks associated with hyperthyroidism, you become conditioned to them even if you are not normal. I wouldn't wish hyperthyroidism on anyone.
I have Graves' and was hyperthyroid for years before figuring out what the problem was. My symptoms slowly worsened over time until I thought I was going crazy. I was nervous, shaky, irritable and exhausted. My thoughts were always racing, my body always hurt, my heart rate was dangerously high, and I no longer felt like myself.
Six months after RAI, I became very hypothyroid because my dr at the time was not up on thyroid care. He wouldn't medicated me because my TSh was .001. I having severe charlie horses with any wrong move, was so tired, swollen, moving very slowly, emotional, losing hair and depressed. I can say this was the worst I've ever felt in my life. I felt like my body was shutting down.
Being Hyper was an awful way to live and in general is worse than being hypo. I've lived a pretty good life the last year even though I've still been hypo. But, for those who become Severely hypo...I don't know if there's anything worse.