Long term... and I do mean long looooong term... here is what we're looking at in no particular order.
Earth.
This is the planet that needs terraforming the most. We've seriously fucked this planet up, but the good news is that it's fixable, and it will be the easiest to fix up. This is our highest priority. We do this, we can do everything else.
Mars.
As the infographic explains, there's lots of ways we can go about it. But Mars is definitely a worthy candidate for terraforming. It will likely be one of the first worlds with any noteworthy colony on it. One of the biggest setbacks involves the lack of a magnetic field but it's possible we can overcome this with science and technology.
Venus.
Venus can also be terraformed, however it will require a bit more effort. The best concept I've seen involves slamming hydrogen ice asteroids into the planet repeatedly over a long period of time. This should cause a Bosch reaction converting the carbon dioxide into water and graphite. If we do this enough the greenhouse effect will diminish and the atmosphere will rain back down and reform into oceans.
If we aim all of those previously mentioned hydrogen ice asteroids the right way, we would be able to impart a slight increase in spin to the planet, though we would need to do more. This is Venus's main drawback. How do we get it up to any decent spin? It would require an enormous amount of time and resources to accomplish but theoretically it's doable.
Europa.
Europa is another candidate for terraforming. The main problems for it will be the high levels of radiation coming from Jupiter, low gravity, and the risk of the moon entering Jupiters shadow.
We'll want to build up a thick atmosphere for the moon, and possibly move it closer to Jupiter. Doing this will increase tidal pressure on the moon which can create a magnetosphere. Between the two and supported by other methods, this would solve the surface radiation problem as well as ensure that Europa is in a controlled orbit to avoid the moon from freezing back up in the gas giants shadow.
Even once we have done this there will be problems involving where to build. The whole world will be an ocean, so this will require creative solutions on it's own, but I think if we get to this point, this part will be the easiest to solve. It's gravity will always be a problem. It's possible biological science can come up with a solution to this, though we might just end up with humans adapted to different gravity in the future. I.e. Europans will be fine, but they can't come to Earth. Earthlings will be able to go where ever.
Enceladus.
We know a bit less about Enceladus but from what we're seeing it would be similar to Europa with a few exceptions. One being that Enceladus lacks a metal core, which means we wont be able to get a magnetosphere created, so we will need some other solution to Saturns radiation belts. It also orbits fast enough and at a distance such that Saturns shadow will never be a problem for it.
The biggest problem is the moons extremely low gravity at about 1/100ths that of Earth this is problematic. I don't really see any plausible solutions for this problem and this will most likely prohibit serious colonization of the moon unless other extreme methods are utilized, such as spinning the planet up to where surface negative g's would allow for inverted subsurface colonies, of course this precludes terraforming.
Long term this might just be the simplest solution. We will almost assuredly need to colonize the moon to take advantage of it's water wealth but this is the least likely candidate for terraforming.
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As to other possibilities, who knows? I don't think it's possible for us to know what we will be capable of in a thousand years. This is almost all speculation at this point based on what we know now. I think the take away here is that we have a lot to look forward to as a species. The hardest part of all of this will be the next 100 years. We have to get over our bullshit here and work together to exploit the nearly infinite material wealth of out universe. We're like two kids fighting over a grain of sand while standing on a beach. It's time to grow up.