Since this topic is already a 90 page shitstorm let's add a bit more to it. I think 5 member party size is the optimum. Prove me wrong over the next 90 pages. Have fun!
Um, when it comes to opinions, it's your job to prove yourself right, not someone else's job to prove you wrong.
Just kidding obviously. Never understood why some people on the forum are so determined 6 people in party is a determining factor for anything. I've read pages and pages of people trying to prove their point about it. The only one that actually makes sense is party compositions might be a tad more intereseting with 6 characters since you have more classes to mix together. But ...that's it. Everything else is really a matter of taste.
Is it? Maybe you missed ALL the reasons I've given previously as to why Party of 6 makes more sense for this game. It isn't just a matter of taste.
What about:
1. Party of 6 allows for Party of 4 actual Players in multiplayer mode and 2 origin characters, thus allowing people to play together and still have a couple of character slots so you can do origin character story missions/quests and so forth - allowing for origin character dialogues and so forth with a full party of 4 players. 2. Party of 6 allows for more party dialogues. I did the party of 6 mod where you tweak the max party size number. I hate mods, but I made an exception because I cared about this one so much. Turns out, your characters have a lot more dialogues and seem more like a cohesive party and unit when you have 1 Custom Character and the 5 origin characters all traveling together in one party at one time. Yes, they actually talk more when you have all of them together. 3. Party of 6 allows for less frustration in tougher combats. For example, if a duergar shoves Lae'zel 30+ feet into lava for a 1-Hit KO, you still have 5 other party members, meaning you aren't quite as hindered in the fight as you would be with only 3. Instead of losing 1/4th of your team in just one stupid move, you only lose 1/6th. Still a sucky thing, but you can live with it. 4. You can carry more with a party of 6, meaning you don't have to manage items as much, constantly shifting things around or sending one item at a time to camp because you just can't pick up that beloved spoon you spotted in the treasure chest in the basement of the toll house. When I was traveling with the party of 6, I could easily spread out the items and keep going without having to stop and manage them so much. (This one wasn't as big a deal for me, but it was still something.) 5. Party of 6 makes it so you don't have to constantly return to camp and switch out party members when wanting to do an origin character side quest like Lae'zel and Zorru or Wyll and Spike. You can keep all the current origin characters with you all the time and not have to worry about constantly switching them out. 6. It makes more sense that if you are going to go face a squad of gith who have a dragon, that you might bring everyone you have with you for the fight. Makes no sense to be "full up" with a party of 4 and then go to face some super tough enemies one-on-one. If I'm going to enter a phase spider matriarch's lair or face a horde of goblins, I might want to bring a bigger party. 7. Combat would be actually more balanced with a 5e ruleset if they implemented party of 6 instead of party of 4. EVERY combat currently is a Deadly encounter if they were to actually implement 5e rules and stats for monsters. 3 Imps against 2 Level 1 characters is insane. 3 Imps against 5 level 1 characters (4 custom and Lae'zel and/or Shadowheart) is not so insane. Same with 3 intellect devourers. Same with skeleton magic users. Same with actual bandits/mercenaries. Same with gnolls on the road. Same with 4 githyanki. Same with phase spiders.
I could go on and on and on and on, as I have in this thread, but I think that should be enough to show that it's more than taste. There are a LOT of gameplay elements that are currently hindered by a party size of 4. Again, party of 4 limits people who want a party of 6 while party of 6 does not hinder a party of 4.