bitcoin is good for short and longer term of investment. etherium is a stable coin that is also good for longer term of investment, you can then add other promising coins like ripple, bitcoincash, and iota to to be able to have a solid portfolio and at the same time while maximizing your potential gains. just remember , dont put all your eggs in one basket in order to avoid loosing that much if one of your chosen coin has failed and always make bitcoin as a primary source of investment and the rest are just additions for an even extra income because bitcoin cant always sustain you a substanial gains.