I prefer bitcoin portfolio with a little of other altcoins. I'm confident with bitcoin for it has proven over years of its outstanding performance. All other altcoins are still promising. Its better also to have it in time that its price is still very affordable. Indeed, its really best to have it all but more of bitcoin to have many options in case one fails.
This is I prefer invest in bitcoin and some altcoin. At this current stage my top investment is in bitcoin and some altcoins which I believe price could soaring high once the market is in bull run. Diversify portfolio is indeed a good option but never invests in an altcoin that is not profitable in the long run.