I could understand a case for any of those. Notice that it isn't "you have 25% more muscle," it's you build muscle 25% more easily. The reason men are stronger than women is because testosterone facilitates muscle growth. I dunno how much of an improvement 25% is, but if we simply think of it as the capability to develop more readily, that might make it more enticing to actually spend time at the gym.
Fat burning isn't actually all that bad since the implication there is that you have a higher metabolism. Metabolism = more energy. Often a lack of energy is what people struggle with, regardless of the amount of sleep they get.
Intelligence, well, the problem for me with that is that there are different kinds of intelligence. Like, a highly skilled athlete has brain tools that another person of their stature does not, which is the real reason why someone (that isn't a giant) is so much better than another at basketball. There's musical intelligence, linguistic intelligence, mathematical intelligence, social intelligence, et cetera. http://en.wikipedia.org/wiki/Theory_of_multiple_intelligences
It was also never clarified if we're talking about starting a new game+, or if we just leveled up and get to pick a new perk.
How about some other bonuses?
5. Social Graces
-You are generally more well-liked, and more astute at saying or doing the right things in situations involving human interaction.
6. Power of Attraction
-Members of the opposite sex would rate you a couple points higher on a scale of ten on account of more attractive facial features, an improved body shape, and other X factors that do not overlap with the other bonuses.
7. Improved Health
-Choose any one health ailment that you have or would be predisposed for. It no longer affects you. Examples of choices include allergies, diabetes, poor vision, depression, Alzheimer's, or erectile dysfunction.
8. Mental Strength
-You are generally wiser, have greater willpower, and are more resilient mentally. You are more likely to make better use of your time, to finding the practical solutions to problems, and to dealing with adversity.
9. Fast Learner
-Though you are not necessarily more intelligent, you are quicker to understand new topics or to pick up on nuances of a particular craft. You may choose to be a Fast Learner toward academic pursuits, practical applications, or a partial combination of both.
Would any of these outweigh everyone's desire to gain extra hours in the day not needing to sleep?