I would say bitcoin core is one of the best, because some people value security the most while some prefer to have a convenient set up.
The current blockchain is over 26 GB already.
We have about 140 new blocks a day, average block size is about 300 KB (https://btc.blockr.io/charts), and so if you open the bitcoin core program once a week, you should prepare to download roughly 294 MB of data every time.