Which has a tougher campaign, COD or BF?

I don't typically like playing military shooters (I have my reasons...) but since I had the chance I played Battlefield 3 and 4 for the heck of it and beat them fairly easily solo. So if that's as hard as those get, is Call of Duty any better? Mind you the most of COD I've played is in multiplayer when I'm at a friend or relative's house and what little campaign I've played I've never done solo or finished, so I can't recall if its any tougher than BF3 or 4.

Before anyone says anything just note: I'm well aware these games are better in multiplayer, I'm not looking to discuss which game is superior to the other, I can do without the fanboyism, I just want a simple answer to which game has a tougher campaign.

I don't think either game series is known for a challenge. They are designed in a way where it is more about just going along for the ride and enjoying the spectacle. I never struggled with any of the games with either series. I have only played on default difficulty though. You can always crank up the difficulty I guess.

BF is "tougher", for starters "cover" in any of the BF series is no bullet/explosives proof as it is in COD.

Battlefield, even though COD is more enjoyable.

COD WaW is a challenge.

More like a beatdown.

Anyway, the hardest part of Battlefield campaigns (including the two Medal of Honor games for good measure) is overcoming the boredom for how dull they are, exception made for the two Bad Company campaigns which are quirky and funny, with a bit of an A-Team vibe to them

CoD needs to be played on Veteran if you want any amount of challenge. and even then it depends on the game: MW2, MW3 and Ghosts are really easy even on Veteran, while Black Ops 1 and 2 and especially the accursed World at War are quite tough, mostly because of poor game design. CoD4 is also nightmarish here and there on Vet.

COD 1-WaW on Veteran are tougher than BF campaigns.

CoD

I did crank up the difficulty, the first time I played I immediately started on it's hardest difficulty and had I started early in the day rather than late at night and didn't take breaks, I probably would've finished well before midnight. What you say though makes sense, they feel like they have more frills than thrills...

Also to everyone else thanks, if I get the chance I'll give WaW's campaign on Veteran a try.

@DJ-Wolfman09: neither of them are challenging, i do find that COD gives you less options and limits you to attack the situation in a certain manner. In BF4 you get the weapons you want and you can attack the situation how you want. But they're pretty much the same

Both are eazy but really it differs from player to player two factors are: The skill level of the player and the playstyle.
For me they are both casually eazy but for the other it can be almost impossible

Battlefield 3 and 4 campaigns are horrriibbllleeee

COD series