Pwrsonally I don't see any other coins that are worth daily trading besides Bitcoin. Also, day trading is very demanding, it requests a lot of experiences and knowledge and your full attention to the market so it would be very hard to follow this for multiple coins. But maybe there are some successful traders who could manage that also.
I think the same, I like to trade with bitcoin and ETH because for me both of them are really good coins to trade for day, as price rises faster in day trading, it has more potential and it is first crypto currency, we will see progress even more with passage of time, trading is the beneficial only with bitcoin not any other coin.
I do not think there is just Bitcoin out there in the market that can make or generate value in the market. ETH and Litecoin are good as well. There is a long list of good coins but if you do the relative analysis, you would realize that Bitcoin on the average gives more profit than others do so yeah Bitcoin is relatively good. But investing in a wide range of coins really makes you able to cash the profits due to diversification.