The best thing, according to me would be to sell 30 to 40% of your bitcoin and buy into other top 20 to 30 coins as per the largest market cap and hold on to them for the years to come.
You will be able to diversify and reduce your risks.
That strategy is good because as of right now the bitcoins price is going very high and it is still going up , and the higher it is the less people will be able to get their hands on so their best option is to switch the top altcoin that are close to bitcoin , because they will be easier to mine to get and the exchange rate will go higher the higher the price of bitcoin will.
That is assuming that somebody has the hardware and or knowledge to mine the specific altcoin that is the flavor of the month.The problem with picking an altcoin is that the altcoins that are the most profitble to mine and or "day-trade" can be extremely volatile and even though you may profit a little bit from some coin. Then that coin will crowd out with miners and then you wouldn't be able to get such good profits.
The best way that I have seen to just hold money regardless of this "Sell-everything" mindset that people are talking about is to hold Bitcoin through this growth period and then once Bitcoin stabilizes a little then invest in a different coin in the end. However, we won't know what this coin will be until the bubble has ended.