Ryan, but only because Biden lost it.
I'm biased toward Ryan on substance, but taken as a debate and only on what was said in the debate, the substance of the two more or less balanced out. It was he said, he said. No clear and away winner as far as one of them having the better case as presented.
So, style and presentation and command of the debate: Biden drove the debate. He did it by interrupting Ryan at nearly every point he started to develop a cogent point of argument, which broke Ryan's stride and had him wasting a lot of his clock restating in order to present a coherent statement, at which point Biden would interrupt again. As a debate strategy it works, when you're allowed to get away with it, and Biden was allowed (by both Ryan and the moderator). It diminished the debate as a whole and made it borderline unwatchable, but it is a time honored way of seizing control. Point, Biden.
So if Biden was even on substance and ahead on control, then how did he lose? Because of his demeanor. The smiling, the laughing, the dismissive remarks at the start of each of his time periods, the malarky, the stuff (Irish you know)... He made it damn near impossible to watch the debate he was otherwise on pace to win. I'm guessing that a great number of people started off watching the debate and by 30 minutes in there were maybe 2/3s of the initial viewership, 45mins in, half. And it was probably independents and undecideds that were tuning out. They aren't going to remember what the candidates said. They're only going to remember "the Biden guy was an *censored*, I hate people like that". Leaving only his base, who probably gobbled up the aggressive tone and over the top asshattery of his demeanor as a nice consolation after the drubbing Obama took last week, and the republican base, who wanted to see what Ryan was made of and see if the team could pull off another runaway upset.
So Biden lost it by being a totally unlikeable douche during the debate. This was not the expected way he was too lose, if he was to lose at all. Biden is affable. He says the darnedest things, but he's generally a humble, everyman sort of guy that is easy to like on a personal level. He connects. Tonight he was not the Joe we've known all these years. He was an ass, bestowing zero respect on his "friend" he was debating or the people watching. He was not presidential in the least. He was barely adult.
For his part, Ryan was a bit too accepting of the interruptions and smug dismissals. He let himself get dragged off point a couple times and in recovering from interruption he lost time in the rehash. He had his facts and figures. He had his arguments. He wasn't smooth in delivery all the time. He stumbled here and there and left some easy points of argument on the table. However, he was presidential, even if not the best debater in the world. He held his own against a seasoned veteran of the game, even when that seasoned veteran was borderline manic in his presentation. He did no harm, but he did little good either.
What lessons can be gleaned?
1) Obama can be a bit more aggressive in his style next week, but he can not do what Biden did, no matter how much his base might like it. Romney was aggressive without being an ass about it. He was respectful and at least came off as sincere. His interruptions were usually short lived and just to clarify a particular point Obama tried to get away with. Biden interrupted too, but he did it not to clarify but to obstruct and at times seemingly to filibuster. And his demeanor before, during, and after made it all come off as unseamly and uncomfortable to watch. Obama needs to be careful not to fall into this same trap.
2) Romney needs to put a little more meat on at least some of the 5 point plan. Pick one or two items and intend to put out some specfic ideas he will present if elected president. Don't phrase them as promises or anything. Say, here's some ideas on how to get 12 million more people employed in X years time. They may not all happen, there will be other ideas I put forth and that the democrats will put forth. This is a starting point and ideas I know will work. Same for tax reform, particularly on deductions he'd put on the table along with his tax cut plans. He should be prepared to do this on each of the 5 points if pressed by Obama or the moderator, but he should come with the intent to actively get ideas out there on two of the points of the plan. He's already done this in pieces over the past few months, he needs to present it and consolidate it into the town hall "debate" next week. The town hall format will lend itself well to this. The format will largely prevent interruptions from the opponent. You basically get 2-4 minute blocks of time to make a mini-speech on each question subject.
3) Romney and Obama both need to work the likeability angle. Romney got a big bump on the likability question from the last debate. He needs to solidify that during the town hall. Can't be stilted or canned in his responses. Has to connect and present a majority of the answers in terms people can grasp simply and perhaps even emotionally. Obama has the opposite problem, he lost likeability in the last debate. A little bit of Biden's stench will follow him too. He's got to reestablish on this front in order to have a chance at getting the independents he lost back in his camp. The town hall format should aid him greatly in this effort.
4) Romney needs to have some lines of attack to bring to bear on the recent unemployment reports (monthly and latest weekly). The numbers are out of whack good. He can't take the Jack Welch line of attack (at least not without some clear proof of how the numbers were fudged), but he has to be able to point out how the numbers are almost surely going to be "corrected" in the next report because the figures in there simply do not make a lick of sense given the poor GDP growth we've been operating under. Does anyone seriously believe over 800,000 people found either full time or part time work in the last month? How does the college age demographic actually show job growth in Sept when that month always shows job losses for that demo historically speaking? And news today that the latest weekly numbers are skewed by one large unnamed state having been late to get their figures reported to the BLS. Obama is almost surely going to tout these unemployment reports and try to fold it into a "things are getting better" narrative. Romney needs to be able to undercut the reports without looking like he's undercutting America or being capriciously partisan, and in a way people will grasp without a chart. Maybe the strategy is not to directly undercut the reports, but to focus on what people are experiencing in their lives and communities and how this isn't recovery, it is stagnation and decline in real life terms.
One last thing: Libya, Fast and Furious: I don't know if it will hit the fan for Obama in time for the next debate, but the way the attack in Libya has been handled has been an unmitigated debacle. It is either gross incompetence or a work of internal administration sabotage unlike we've seen before. Either way it isn't good and there's no way the media is going to be able to keep it from glowing red hot for weeks. Similarly, the F&F scandal festers. The univision special report exposed a whole other side to this thing that is arguably far worse than how it played out domestically with the killing of one or two agents. And now the attack that resulted in a death in Yemen. Iran nukes. Obama is highly vulnerable on the foreign policy front. I don't know how much of the town hall will play into this subject area, but the last debate is all foreign policy. It's going to come at him and he has to be ready with more game than what his administration has brought on these topics in the last month's time.