Ah, the dreaded co-op claims. "It might as well be solitaire", "One player just tells everyone else what to do", "It's play-by-committee", "An alpha player (translation: a bossy jerk) tells everyone what to do".
I'm going to use PbC (play-by-committee) in this post, because it abbreviates nicely and is less judgmental than APtABJ.
There's a big push to make co-ops resistant to PbC, with varying degrees of success. The list below is an attempt to group co-ops by how much the game does to discourage PbC.
A few things to note:
* PbC is very subjective. Some groups won't have 'problems' with it in any game. Some groups will manage to make it a problem in any game.
* I'm ignoring traitor and 'one player wins' options. That's a competitive game, not a cooperative game. Incidentally, including such options don't necessarily reduce PbC; players may be even more pushier about "correct" play when "poor" play may indicate a traitor. As such, any game in the list below only considers true co-op play, even if the game includes other options.
* PbC is highly subjective. I've repeatedly observed that posters on BGG tend to PbC less when a game has more of a classic RPG look and feel to it, regardless of the actual mechanics of the game. I am only going to consider the actual mechanics of the game. You'll have to decide for yourself if you would push a new player to spend 2 blue cubes but not to spend 2 magic points.
* Finally, I feel the mantra of "no PbC" is a sad thing for co-ops. While it's so often cited as an automatic problem, I think the experience of planning closely and debating tactics with your friends can really be an awful lot of fun. True, such games work best when everyone at the table is at a similar level of experience and vocalness. But there are many, many games that work best when all of the players are at the same skill level. By continually striving to avoid PbC, I think some game designers are working too hard, and maybe making a game worse, to fix problems that aren't really problems for many players.
On to the list!
Impossible to PbC
These games specifically feature limited communication. Managing the communication limitations is central to the game and makes it impossible to dictate play to other players.
Onirim (assuming you use the "no-talking" rules, which I recommend)
Very hard to PbC
These games all feature real-time elements. Because players must go very fast, it is hard to play for others. In some situations and with sufficiently experienced players, a player may be able to do so however.
Escape: The Curse of the Temple
A Little PbC Resistance
These games have limited measures to reduce PbC, such as small amounts of hidden information or hands of cards that are too complex to easily PbC. A determined player may be able to PbC in these games.
Defenders of the Realm (this one was a tough choice; could easily go down 1 category)
Hooyah Navy Seals
Lord of the Rings LCG
Sentinels of the Multiverse
Witch of Salem
No Special Resistance
The games have no particular protection against PbC. They may have hands of cards, but the card info is limited enough that it can easily be communicated.
Flash Point: Fire Rescue
Lord of the Rings (downgraded per suggestion)
Mice & Mystics
Oh No...Invasion! Apparently this one has varying modes
Prophecy (co-op variant)
Star Trek Expeditions
Warhammer Quest (might go in the "not enough skill" category below)
Wrath of Ashardalon
These games outright encourage PbC. These require or strongly reward close planning that easily lends itself to one player dictating a plan for the group. Several have no definite turn structure; having all the players take their turns at the same time leads to a much more committee based atmosphere and makes it more likely that one player will simply instruct the others as to what to do.
Space Hulk: Death Angel
Not enough SKill to PbC
An odd side case. You could PbC in these games, but there's really not enough for meaningful choices that there's any point to.
A Touch of Evil
Fortune and Glory