Rated as a complete package, my list would go:
1.) Demon's Souls
The original and the best. The game is innovative, compact, and focused. It strikes a perfect balance with its areas and bosses. Each boss and level is unique and interesting, and there's just enough to provide variety without becoming redundant or tedious. The areas themselves are all expertly crafted with each one having internal consistency unmatched by any other game in the series. The story/lore is also fantastic, with each item and NPC situated in just the right spot to provide you with the information you need to put the story together. There's plenty of enemy variety, build options, secrets and hidden paths/items, features (tendency, online interactions, etc), great boss music, and replayability. I think it's a near-perfect game, and have nothing bad to say about it.
2.) Bloodborne
Unlike the Dark Souls trilogy, Bloodborne takes the system built on Demon's Souls, and pushes it in a new direction. Just like Demon's Souls could be said to have innovated on the King's Field blueprint to forge its identity, Bloodborne does the same with the Souls engine. Appropriate for the game originally planned as Demon's Souls 2. The game has fast and fluid combat, great enemy designs, and fantastic variety with different areas and locations. Bloodborne's greatest strength however, is with its story and art direction. In my opinion, it is the best in the series with a unique premise and incredible level, weapon, and costume designs. If I had to knock Bloodborne for something, I would say that it lacks build/weapon variety, and has arguably the worst PvP in the Soulsborne series with tons of fast healing, parry-spamming, and same-y fighting styles.
3.) Sekiro
With the fastest combat to date, Sekiro really earns the GOTY title. Like Bloodborne before it, everything about the presentation is great. Enemy design, level variety, and boss battles are all top notch. It's difficult to pinpoint every detail that makes Sekiro so good because everything about it is just amazing. Unlike the other games, Sekiro introduces an element of stealth that I absolutely love, and as a Tenchu fan, have been waiting for for a long time. If I had any negatives, I'd say Sekiro felt a bit short, and really lacked the hidden paths, items, and optional areas to encourage exploring. An all-around great game, I don't think it reaches the highs of Bloodborne/Demon's Souls, but it is consistent in its quality throughout, and more than worthy of being in the top 3.
4.) Dark Souls
Dark Souls simply takes everything from Demon's Souls and refines it. Removing what people criticized while improving what was kept. It ditches the level selector for an open world which really helps to immerse you in the game, and to encourage thoughtful exploration. It falls short in the second half though with obviously rushed areas full of uninspired enemies and some tedious areas. The covenant system was a great way to improve the online, but most of them feel pointless or unfinished. Level design, build variety, and bosses are mostly good, but there are some serious offenders as well such as Bed of Chaos and Lost Izalith. It's still an AMAZING game by all standards, but I think it falls short compared to the other games above it on this list most likely due to a rushed development schedule.
5.) Dark Souls 2
There's a lot wrong with DS2. There's still a lot to like, but DS2's biggest flaw is that it simply disappoints. As expected with a game that has to be scrapped, and put back together again halfway through development, it can feel all over the place. As for positives, I'd say it has the best PvP in the series with tons of build variety, and an easy way to change your builds which further encourages you to experiment. It had some great ideas like the bonfire ascetics, new enemy/boss locations in NG+, and things like small soapstones. As for bad things, obviously the soul memory system is flawed. Level designs all seem great on the surface, but most levels are full of empty rooms, corridors, and boring/bland straightforward design. Bosses also mostly look uninspired, and the game focuses too heavily on crowd-control, often throwing heaps of enemies on you in order to emulate difficulty. I don't hate DS2--far from it--but I do think it commits the mortal sin of being a disappointing follow-up, and that those expectations and promises it failed to meet will forever stain it.
6.) Dark Souls 3
The Metal Gear Solid 4 of Souls games. By far the weakest entry, in my opinion. Like DS2, it disappointed greatly by failing to meet expectations. For example, the Covenant system somehow manages to get worse than DS2, the level design becomes more straight-forward and bland, the story/lore becomes increasingly nonsensical and convoluted, and the online experience fails to improve over past iterations. Unlike DS2 which took the good from DS and tried to add to it, DS3 seems adamant about ditching everything from DS2, whether it be good or bad. As a result of this, we lost some good mechanics that should have stayed. Additionally, the game focuses so heavily on references to past games, it lacks an identify of its own. It's impossible to go five minutes without tripping over a reference to Demon's Souls or DS/DS2 or picking up a reused item/weapon from one of those games. There's nothing wrong with references, especially in a sequel, but there's a line that shouldn't be crossed, and DS3 leaps over it. Level design is okay at best, bosses are pretty forgettable (with some exceptions), and the story is somehow worse than Dark Souls 2 because it further muddies the already-vague, but consistent lore of DS1. Like DS2, it's better than 99% of other games on the market, but it's by far the weakest Soulsborne game in my opinion. Hopefully this marks the end of the Dark Souls series so that FROM can branch out in new directions.
