I didn't vote because in sum way all of these games are sumwhat of a rival but at the same time not. For example:
GOW - Its epic scale and its consistant story. The team at Sony Santa Monica don't leave huge gaps in the storyline, since they clear everything with either the main console games or the handheld games. The scale of the vistas in the game are really a site to behold, and every enemy has a reason to fight Kratos, or every enemy Kratos encounters he has a reason to fight. With DMC 4...all the bosses were just fodder, and its sad about the potential of Berial. Honestly, the DMC 4 bosses weren't even doing anything.
Bayonetta - Its combat. Aerial Stinger, Canceling moves at your whim, special outrageous abilities. Even though half the characters in this game are asinine (Bayo, Cereza i'm looking at you) i mostly stick with it cause of its sheer brilliance in gameplay. Aerial Stinger is a logical thing that should've been in DMC a long time ago, but Capcom never implemented it. Canceling moves ever since DMC 1's Shotgun Cancel and DMC 3's Killer Bee canceling is pretty stale next to Bayo's combat. The weapons are great and have great origin profiles that fits to Bayo's powers. All the weapons were different and didn't look like sum skin over an old existing weapon from an earlier game (Gilgamesh i'm looking at you) This game i think is a major threat---at least gameplay-wise---against DMC.
Darksiders - Its story reflected on the stages, as in the story reflected on how the stages looked since it was the semi Apocalypse. DMC 3 was good at this since Temen Ni Gru was a central figure in the plot. The ending was a nice cliffhanger (i won't spoil it) but at the same time the story that was in the game was self-contained. Darksiders delved more into the way Hell and Heavenly beings conduct business when it comes to the human world. It was dark and serious and the characters had very good reasons to connect to War. This is sumthing DMC 4is sorely lacking. All of the characters were bland except for Nero, but Capcom managed to mess that up as well with leaving his origin unanswered, thus it created a cheap "cliffhanger" (if you call it that) for the next game.
Castlevania - I don't know about Lords of Shadow. But i think a CV game would be a great template if ever the DMC series went handheld with side stories. Unfornately, Capcom canceled the long rumored DMC PSP game rumored to be called "The Dance of Sparda" and who knows if they ever make a PSP game for DMC. Castlevania is one of the best and is the most relatable to DMC with its aesthetic. But one thing that CV has over DMC is that even though it can be sumtimes campy, it has tons of info about demonology. That's sumthing DMC lacks as well since DMC 4.
Ninja Gaiden - Not very much competition with this game. I think NG and DMC stand good side by side. BUT NG's sheer goriness with its fountains of blood and unrelenting difficult makes DMC 4's DMD mode seem like a Wii title for children. I think DMC 4's difficulty was a bit balance. But i'm sure people want DMC to be more challenging. Especially DMD mode. To this day i still proclaim that DMC 1's DMD mode is the toughest DMD i've beaten.
Enslaved: Odyssey to the West - Ninja Theory creates beautiful games (even though they can be kinda repetitive in the gameplay department and quite short if we're just looking at Heavenly Sword). But one thing they know how to do is create a very engaging story with great performances. This is sumthing DMC needs. DMC 4 made DMC looked like sum typical anime trash that people are used to and not anything that would differentiate it from the rest of the Japanese type entertainment that makes its way here. I really do hope Ninja Theory is working on this. Cause maybe since they're located in the UK they can bring sum English wit instead of the vague Japanese humor and also at the same time bring in an epic story with good acting and dialogue. Don't count out this developer yet. I can't wait to play Enslaved.
In other words. All these games are a rival to DMC in sum capacity. I have my reservations about being on the Hype Train for DMC 5 since DMC 4 was subpar at best. I just hope people don't think that we'll ever get that spark that DMC 1 and DMC 3 let us have. DMC 5 has to let us have a different spark so it can have its own identity in greatness.