I think it has still room to spread a lot and other coins are just following the up trend of the bitcoin. The more BTC will rise this time the more other coins will rise too. You can think about BTC as mother of all (reality) and others are children of it and they are fallowing it in the straight line. So you may wanna choose other coins if you think are in the position to invest money into them and wait for very long time. Apart from hat BTC always holds the first choice of investment but for your investment to rise quickly it will take little more time than others as moving 5-6 figures prices is difficult than moving the 2 digit figure in the up trend. The costlier the coin is the more market cap it has keep up for long term sustaining of it. So think which way fits best for you and then you can proceed.