Sword Art Online or Log Horizon?

They've got the same basic premise but I feel like they do pretty different things with their plots. SAO is basically a fantasy shounen with a video game motif and Log Horizon cares more about looking at what it would be like living in an MMO with much less focus on action and drama. The biggest thing that illustrates that is that in SAO everything is life or death and in LH it's a lot more relaxed because you can just respawn.

Since they go in such different directions I'd say there's not much point comparing them. It's all subjective in the end. I don't like SAO too much personally because Kirito is the Maryest of Sues and it got a lot less interesting past the first arc. Also the other characters are almost totally irrelevant. But anyone who wants to like it is welcome to.

I'd say log horizon. SAO definitely has a good concept and plot but the characters lack a lot of depth and I dont really see any significant character development. In my opinion a lot of the main characters are very static. Log horizon focuses more on the setting and how the characters utilize it to their advantage. Also, the characters are all very interesting. ((as you can see I love good characterization lol))

SAO is good but loses steam in the second story arc, but I really enjoyed it. I haven't seen Log Horizon, but would also recommend .hack for a similar setup (cant remember exactly which series)