Right now there are more coins available in the market which gives you more profit than bitcoin.
Bitcoin price is also not stable.
All these factors affect its popularity ??
What you think, still bitcoin is more popular ?
Bitcoin is still the origin of the altcoins since you will need to buy bitcoins first before converting into those coins. Since it is the first step before the altcoin, it is much popular than those coins. Those coins are actually made for bitcoins since it is much better and the company got more knowledge about btc, they handle it better so people will buy them and have more profit than the usually investing in bitcoins.