I feel like DS3 before you reach Irithyll is pretty tame for a Souls game. Once you reach Irithyll it definitely gets harder than DS1 ever was, but by that point you probably are at least okay at the game. The beginning of DS3 is a lot easier imo than the beginning of DS1, plus it’s a more polished game in general and looks and feels nicer so I could see a newbie pushing through more with 3. ER is definitely the easiest to get into as a newbie though. Spirit summons make fights a lot easier since aggro is split between you and the boss, without increasing boss health like you’d get with NPC summons, and the open world lets you just fuck off and do whatever to avoid a boss until you’re better, or skip the boss entirely depending on who it is. It definitely ramps up the difficulty end-game, and the DLC is probably the hardest content they’ve ever released (though it’s also the best imo), but the first portion of the game is way easier and more beginner-friendly than DS1.
Fair, you need pretty good reflexes to get good at Sekiro. The nice thing about it is once it clicks it gets far easier, but it’ll probably take several hours to reach that point and up until then, it’s going to be a very steep learning curve. Not to say it becomes an easy game by any means, but it’s no longer an uphill battle anymore. It’s still a FromSoft game and has their signature difficulty, and the final boss is still one of the hardest fights they’ve ever made, but it becomes a fair challenge at that point. The first part before it clicks for you will feel unfair and brutal.
I’ve always been better at humanoid bosses than monster bosses so I didn’t actually struggle that much with Malenia, plus I usually use the biggest weapon I can find in any game and she has practically zero poise so I staggered her a ton, but I agree on gank bosses. Godskin Duo can fuck right off, that’s one of the worst bosses they’ve ever done imo. Just trying to recreate what O&S were in DS1 while apparently forgetting what made that fight so good. Weirdly enough my hardest and most hated boss in ER (other than Duo) is Astel, which sucks because it’s a cool design and blocks progress of Ranni’s questline, but any time I die it feels unfair and any time I win it feels like luck. I don’t get that feeling with any other fight. As for Elden Beast, most of my wins against him were before they added Torrent in that fight and I agree, it wasn’t great. I have fought him with Torrent though and it makes it so much better. It’s seriously night and day. It’s still not a good fight, but it’s far less terrible now. I wish it was a better fight, it’s such a cool design and the lore is really interesting.
Dancer is my favourite from DS3 too. She was my favourite boss fight ever until Shadow of the Erdtree, which holds my top three favourite bosses now, and brought Dancer down to #4. Sister Friede is another favourite of mine, though I never found her as tough as most of the community. I’ve only played that DLC twice though so maybe I got lucky both times. Demon Princes weren’t very fun for me, but the DLC bosses got better. Gael is awesome, though I had the same situation as with Friede, finding him a lot easier than the community, but Midir is tough as nails and is the only boss I’ve never beaten. I still can’t get him even past half health. Like I mentioned before I find monster bosses harder than humanoid bosses so that could be part of it, though I found Bayle to be tough but fair.