Alrighty then. I have some experience with the game now. Tried a couple of different builds and beat some bosses. The only boss not included on my list is the Darklurker because I have not fought him yet. The order of bosses in my list might look a bit derpy because I'm using the one from the wiki.
http://darksouls2.wiki.fextralife.com/Bosses
The Last Giant: I don't wanna start off by sounding like a bragging asshole, but he has never killed me. He is the first boss so it's logical that From doesn't want to scare players off, but he is way too easy. His moves are easy to read and he's slow as hell. Any type of build can abuse the "stay close and mash" strat. Very much like the Centipede Demon from DS, just mash until he stomps. Run away from stomp, repeat.
The Pursuer: Alright what kind of difficulty spike is this? You're lucky there are ballista's in his boss fight. He is pretty doable when you spent some levels and upgrade a weapon, but the average player doesn't even get a good weapon before his fight because it's so early in the game. I don't think I've ever taken the time to fight him the "legit" way. I just shoot him with a ballista.
Executioners Chariot: Fun little fight. It's different. It's easy once you make him crash. It has some very derpy AI tho. What I mean by that is that he will never attack me once I'm in the little gap at the side of the road, so to speak. Kind of like what Gwyndolin was in DS, different but not hard.
Looking Glass Knight: It's fun. This was the first fight in the game where I had to try over 4 times. He's hella resistant to a lot of things. I also like how he can summon other NPC's and even players. This felt like my first time in Dark Souls.
The Skeleton Lords: Eh. They go down before you know it. Fun little twist when they summon skeletons out of their corpse but those are even worse.
Flexile Sentry: At a low level this is a pretty good fight (let's not mention that you can cheese him behind the pillar). Small little room so you need to keep moving. I like it.
The Lost Sinner: This is a good fight. It's a strong and fast boss and it's hella dark. I don't just mean the area but the lore behind the character too.
Belfry Gargoyles: Fun little throwback to the previous game. I will probably never fight them again because you simply never have to go there.
Ruin Sentinels: I feel like this is the bane of new players everywhere. Kinda like Pikachu and Snorlax from DS. It's a solid difficulty. It feels like Dark Souls but cheaper. When you are at the bottom and there's more than one of them alive, it's hella annoying. They're pretty dodgeable so that's good.
Royal Rat Vanguard: What the fuck is this? Picture this if you will; You walk into a room with mad amounts of rats. You just start smacking em, waiting for a health bar to go down, or a boss to appear. Suddenly there falls another rat with a GIANT FUCKING MOHAWK from the ceiling. You smack it and it's dead before you know it. Hurr durr what an accomplishment.
Royal Rat Authority: It's pretty much like Sif from DS but with a shittier hitbox. It feels unfinished. I Always get hit from air here.
Scorpioness Najka: I like how you can finally summon an Original NPC here. She also reminds me of Quelaag, which is good. Fight was not really hard. Her spells are easy to dodge and she had mad recovery.
The Duke's Dear Freja: "Hurr durr there are only two parts that you can damage." Alright, let me spam projectiles.
Mytha, The Baneful Queen: How is anyone supposed to know you have to burn the mill down? I looked online for this and I don't regret it.
The Rotten: I like how you can summon two NPC's and just wait for them to kill it. It's a good boss. Easy to dodge and get some hits in.
Old Dragonslayer: Ornstein <3 I like this fight. You can strafe and roll the fuck out of him but it's Ornstein so it's cool. I like how it looks like he walks out of the fog too, like you're a boss for him (and you are).
Covetous Demon: LOL
Smelter Demon: Why is this guy optional? They make the actual good boss fight optional, but then you HAVE to do the easy one. Come on Dark Souls, this is not why I imagined.
Old Iron King: This is the easy one I was talking about. A really slow fuck chilling in the lava. Dodge, hit, repeat. Because he's in the lava he can't move far and is hella predictable.
Guardian Dragon: Pop a buff, rush in and he's dead before you know it. Like I said before, if he stomps just dodge out of the way and repeat your R1 spam strats.
Demon of Song: I love his design. I also hate his really fast charage move. That is the one time he killed me, when I didnt know he had that move.
Velstadt, The Royal Aegis: Very good boss fight. First time I saw him I died a lot before I met my old trusty pal, Sunlight Blade. The hitbox on his weapon is very messy tho.
Dragonrider and twin Dragonriders: Strafe and mash. You can also make the first Dragonrider fall off. The one with the bow has no health at all. Very derpy and easy bosses.
Prowling Magus and Congregation: They don't even have any attacks that will hit you. Why are they bosses? Is this the DS2 Pinwheel?
Giant Lord: Basically a buffed Last Giant. Stay under him, mash R1 on his legs, pop estus behind him when needed, repeat.
Throne Watcher and Throne Defender: Why is one of them watching while the other one defends? The names still puzzle me. I like this fight. Not too hard but that's because they prepare you for the final fight, RIGHT?
Nashandra: That was the most anti climatic ending ever. Of all time.
I hope no one realized that I got bored towards the end of typing this.