You will need more than 120 gbs for storage. Get both if possible. There are hybrid drives available but both is the best option. The hdd is more necessary than the ssd in regular use. Some of those hybrid will fit an os and a browser in an ssd like speed while the rest is storage.
Well depends on what you do, if you are playing a lot of games, videos and something like high capacity programs then you should get a hard drive ofcourse but if you are not into games and using a computer for web and work then a single 120GB SSD is enough, I have a 120GB SSD since im not into games it is enough for me.
But if money is not a problem consider to get both. hard drive for data and ssd for boot.
For SSD's I recommend Samsung 840 Series or Kingston HyperX 3K SSD.