Currently the leader in the SSD game is the Samsung 840 Pro series
The size of your hard drive is really up to you... do you use the cloud for most storage, do you have high storage needs in your PC, I think 1TB is about right, I'd say 500GB would be a minimum HDD storage unit for games only. But, an interesting phenomena in computing (at least that I've noticed) is that as your storage capabilities increase, so do the amount of things you decide to store...
edit: in response to USAFRet's 840 EVO statement, I was going to include that as being a better value and close to the 840 Pro in performance
Both are correct, the Samsungs hold the top spots in the SSD game, but not by much, OCZ is hot on their heels and even Intel is pushing for more. The Samsung 840 Pro is built as a workhorse, designed for constant input/output of massive amounts of info, and to last 15 years or more. The EVO is not quite the workhorse, but really close, and should last 10 years or more. Considering the average age of a gaming system able to keep up with current games, even 10 years is well beyond the limits of playability. It would be like trying to play Battlefield 4 with a Pentium II 350MHz, on a Voodoo2000 16Meg card running Windows 98SE.
So with the EVO costing less than the Pro version, for basically the same quality SSD, the EVO is currently the favorite.
Honestly, you really don't need a HDD, any storage unit will do, HOWEVER, for the average gamer/user/surfer a 1TB is extremely cost prohibitive and totally overkill. The SSD is basically for your OS and stuff where speed is essential. Non essential data such as music, photo's etc are regulated to a HDD, and only come into play when called up by the OS, so are worked with at SSD speed anyways.
1TB drives are pretty much a minimum spec with Seagate and WD in competition for those honors. Anything more will remain mostly unused unless you have a LOT of songs/photos/games etc, so why spend more on something you aren't going to use.