Fallout 4= Better gameplay and companions.
I would argue that it isn't better in gameplay, but that is all a matter of opinion. The gunplay from new vegas can be improved simply by changing the sound effects so that they sound a bit less like "pop guns." Sound adds a great deal to the "feel" of weapons in games. Fallout 4s sound effects are punchy and loud. New vegas sound effects are low and snappy. You and I talked about it, or rather, I talked about it. The laser weapons of fallout games have loud noises and recoil, but why? You are shooting light. The reason is, without sound and recoil, the laser weapons would "feel" like garbage. As for the companions, watching them empty their weapons into walls, other static objects, other NPCs, or throwing grenades at their own feet, kind of defeats the "better AI" argument, and that goes for enemies and NPCs in general too. I've heard you applaud the AI before, but what you've described isn't AI at all. NPC's speaking with each other isn't advanced AI. It's RNG scripted dialogue attached to simple code that makes them seek each other out while you are around. A very simple AI really. It seems impressive because bethesda spent a huge amount on voice acting and dialogue, which means there are a lot of potential conversations that might happen. New vegas had the exact same system, but with less potential dialogue. Fallout 4 has great sound design, but that is no surprise considering that's where the money went.
Do we have a release date for that mod AJ showed off? or is it out already?