There is still some time to go yet with two masters to be played and who knows how the US Open draw will pan out.
Still, this has been an excellent first take discussion. I'll include my first take analysis, based on what we know now.
Assumptions:1. I'm going to assume that the conditions will be faster this year at the US Open, perhaps to 2009 and earlier levels. There were complaints last year about the slowness, and the USTA usually takes those and makes adjustments to the amount of sand or grit in the paint when they repaint the surface each year. We'll see.
2. I'll assume that all top players will be relatively healthy and prepared to play. This may be erroneous, but since we just don't know, I'll make the positive assumption here.

3. I'll use the most recent form of the grass season as "current form". I realize this doesn't always translate to good hard court form, so I'll factor in the previous similar hard court form from earlier in the year, such as Dubai. I'll not place quite as a high a value on the slower hard court performances, such as Miami, or the Aussie Open.
4. Historical form/class - I look at the whole player's career on the surface/event to determine class form. I don't limit history to the past 2-3 years, but I do factor in the trend. If the player is nowhere near the level they were when they displayed that historical form, then I reduce it's importance. Example: Andy Roddick has won the US Open. But I don't think he is near the level he was, so though one can never completely discount a former winner at the event, I do not place as high a premium on Roddick's class, as Del Potro's. Opposite example: Obviously Federer. He won the event 5 straight times, albeit
2004-2008. But he's returned to #1 in the world and never been worse than a final or semifinal since his last win. I therefore give him an extremely high class factor, even though he had the lesser results recently.
So with that, here is my
first take:1. Roger Federer - best class of all, best recent form winning Wimbledon, silver in Olympics, hard court form earlier in the year in similar conditions was excellent, winning in Rotterdam, Dubai and Indian Wells. I think he'll be difficult to beat. His likely #1 ranking also gives him an possible advantage in the draw. Top chances to beat him: Del Potro, Djokovic, Murray
2. Juan Martin Del Potro - good class, won in 2009. Current form, excellent in the Olympics, very good form earlier in the year in similar conditions. It looks like he is very close to being back at his 2009 level. His serve looked very good in his final matches at the Olympics and was hitting ground strokes with incredible pace and accuracy. He's a bit of an upset in the mix here, but deservedly so.
3. Andy Murray - Never won a major, so his class is below Federer, Nadal, Djokovic, Del Potro, and even others that have won. However, his recent excellent form on grass, especially in the Olympics, was superb. His earlier similar condition hard court performances were good this year. So though
it's difficult to rate him above Novak Djokovic, I think Murray's trend is upward and he may be ready to take it to the next level.
4. Novak Djokovic - Historical class at this event is excellent (but a distant second best), but he is the defending champion, with 5 SF or higher results in his last 5 years at the US Open. However, his most recent form in the grass season was somewhat disappointing. His play earlier in the year in similar hard court conditions was also not at the level of 2011. Now, if he were to win Cincinnati, I might change the order here, but
currently this is where I see him. I feel the pressure of trying to equal or better his results of last year has taken a bit of an emotional toll on him. If he can somehow forget all that, and just relax and play his best tennis, I think he he'll do better, but we can't forget other players also want to do the same. It's very competitive now. If he can maintain his health and energy during this part of the season, I see him having a better end to the year than last year. Playing deep in the Olympics, followed immediately by Toronto, Cincinnati, and the US Open will be very challenging.
5. Rafael Nadal - good class at the event with a win in 2010 and final in 2011, however I think he has benefited at this event from kinder draws and slower conditions of last year. I think this is his worst major surface. His recent form, well, it was tough in the grass season, a surprise exit at Wimbledon, followed by a flare-up of his tendinitis and withdrawal since then. Even if he manages to be healthy by the US Open, his form could be suspect. His similar condition hard court performances earlier in the year were good but nothing special, he is a monster on clay and at this stage in his career is rightly focused on that surface. That said, one can't discount him; he like the other 1 time winners at the event has a chance if he gets a good draw and things play out right. I simply can't favor him above the rest at the moment in these conditions.
Of the others,
Tomáš Berdych has a disappointing historical record at this event, and he had a very disappointing grass season. He might surprise, but I think it unlikely at the moment.
Jo-Wilfried Tsonga has a lone QF result at the US Open, losing in straights to Federer. He had a fair grass season, but couldn't rise to the level needed. His earlier play on similar hard courts was good. I can't see him going beyond the QF.
I see
John Isner and
Milos Raonic has potential spoilers/upset candidates. At the moment, I still don't think they can go 7 rounds in a major. Though their service games are top-notch, their all around games are still too limited. Of the former winners, I think
Lleyton Hewitt's game has been on the improve since his foot surgery. I would not be surprised to see him go deeper than he has in a long time - possibly to the QF.
Andy Roddick looked like he had found a little something at Eastbourne and Atlanta, but disappointed in the big grass events. He could obviously upset, but I can't see him going all the way.
Ok, enough from me, long post again. :shrug:

Respectfully,
masterclass