Inquisition was definitely great in that regard. It has around 80,000 lines of dialogue, and it shows!

I would prefer the speech mechanic from Fallout 3 because it is never a guaranteed success. In New Vegas, I would just upgrade speech and just convince everyone to do it for me which isn't fun at all.

I'm going to side with the New Vegas system - the percentage system promotes save scumming better than it keeps immersion, if you ask me. Saying something smart/convincing is a rather silly thing to have be weighed upon chance; otherwise, what's the point of upgrading it if it can still fail you when you've got a tongue of the purest silver in the wasteland? I think a better approach to get people off guard with skill checks would be using a greater variety, so people could use speech then drive their point home with facts you learn from another skill to back it up. I mean, what's the good of pointing out you know somebody's on drugs if you can't do it convincingly, etc.

Building on that, I think there ought to be more things you can be checked on, like DT or the armor/weapon you're using. Rather than always having flat out intimidation, you could remind who you're talking to what you have to back it up, perhaps requiring more power to back up your statements with lower speech. Then, you could finally go to a place like Little Lamplight and invite Macready to actually go ahead and shoot you like he threatens to and see what he thought he could do to Tesla Armor with an assault rifle - that sort of thing.

One that doesn't let you skip epic fights

I think it would be pretty cool if they used both the speech mechanics from fallout 3 and new vegas but mainly use the percentage mechanic, an example would be that the speech check is the percentage style of fallout 3 but whether you pass or fail the speech check you get a different result depending on how many points in your speech skill.

I wish they would hijack BioWare's dialogue options. Just imagine the posibilities with voiceover mods for FO4.

As a die hard New Vegas fan and fanatic for immersion, i rather the silent character with New Vegas speech mechanic. If you are not a carismatic character, you don't level speech or barter, otherwise, you do. So i think this should be more applied, like, you are a Old Hermit or a Misanthrope(if i recall correctly) you have lines with way less words, as you are a man who doesn't talk much, but still have a option to persuade using a skill where you are good, like intelligence, perception or strenght, etc. It is already is on New Vegas, can't recall if F3 is like this, but for F4 it should have more depth, giving you less or ever more options depending on your Charisma, rather than speech it self, because you can put charisma 1 and level your character puting points on speech, so it doesn't make much sense. Try in real life see a dude that doesn't talk much try to persuade someone using his "charisma", it doesn't happen.

And as for the voiced character, i liked voiced characters in games that the personality is already made. Because in games like TES, Fallout it's better not having a voice, 'cause when you read the sentence of your choice in a conversation, you are already being the character, and the voice you have in your head, or even if you read out loud, you are already giving your character voice. That is why it works in games like Mass effect, the witcher and stuff, they already have a personality, the only thing you do is choosing which way the wind is gonna blow.