Before I can even begin to decide, I'd have to start by identifying and prioritizing what are the most important desires for my life. For myself, lets say health/safety, wealth, happiness. In that order. Happiness is ranked lower because it is generally a side-effect from satifying the previous two.
With those goals in mind, here's how I analyze each pill.
Yellow Pill: I'm assuming that this only lets you read a person's surface thoughts, not their memory. This makes the pill of questionable usefulness. Most people go about the day thinking of pretty inconsequential things that pertain to their own interests. Gleaning anything useful from a person's surface thoughts requires being around the right person (someone who knows something worth knowing) at the right moment (when they happen to be thinking of that thing that is worth knowing). The chances of success go up when you confront that person to trigger them to think of that useful thing, but confronting that person could easily turn into a liability, especially after they catch wind that you know something you shouldn't.
Green Pill: Directly inferior to the pink pill. With the pink pill you could turn into a flying creature. There are many examples why being a flying creature is more useful than being a flying human. Turning into a gnat or other small insect would allow you to fit undetected into areas that would normally be off-limits. Turning into a hawk would allow the additional benefit of superior vision. You would be a fool to choose this pill.
Blue Pill: Unless all you care about in life is to go down in history as some sports star, this pill is terrible. Way too much of a Faustian deal for my tastes. Would never pick.
Orange Pill: This is just ridiculous. If your goal is to get high, the combination of wealth, connections, and privacy which could be attained by properly utilizing the other pills makes this pill directly inferior.
Red Pill: This could be very powerful for the wealth factor if the pill allows you to peer into the private areas of the Internet (such as the email accounts of government officials and financial industry insiders). The information could allow you to time the stock market to great effect, however 6 hours may not be enough time to find the information you need. Not a bad choice, could do better.
Pink Pill: I'm going to rate this pill very highly. In addition to the benefits laid out in my critique of the green pill, this pill allows you to have experiences that would otherwise be impossible in life with the potential to greatly enhance your happiness. Don't tell me you haven't fantasized about turning into a hot chick for a limited period of time, even just in the privacy of your own home. Shape-shifting into another person can also play into the wealth factor if used creatively. If your exploits ever get you in trouble with the law, it would be easy to turn into someone or something else long enough to make a getaway.
Grey Pill: I'm going to lay it right out: love is overrated. You will never find lasting happiness in another human who is just as flawed, if not moreso, than yourself. Ten honeymoon periods is just not worth it in the long run, especially considering that when you are rich you will have all the women coming your way that you could ever hope for. And yes, they will love you as best a woman knows how.
Black Pill: The most interesting for last. So far the Pink pill is the reigning champion. Whether the black pill beats the pink pill really depends on a few specifics. Is the future that this pill lets you see anything you can change? If you see the future exactly as it will happen, no matter what action you take, this pill could be severely limiting. If the future is determined, would it even be possible to utilize this power by making choices different than the ones you otherwise would have made? The "hassle to your daily life" when used publically makes this sound like it could be more trouble than it's worth. What does "using your power publically" even mean? That you allow people know know that you can see the future? Would using this power to play the stock market (wealth factor) count, since you would clearly be indirectly affecting others with the choices you make with this pill? I think this pill is just a little too dodgy for me.
High Tier: Pink/Black
Mid Tier: Yellow/Red/Grey
Shit Tier: Green/Blue/Orange
I cast my vote for the Pink Pill.