Both altcoins and bitcoin are worth buying, it just depends on what you prefer, or what works best for you. For so many, their option would be bitcoin because they feel that it is a safer option, while to so many others, their option would be altcoins because they believe that investing in altcoins might mean getting more profits from them.
Yes, both bitcoin and altcoin are good investment but it not about what ones prefer or want are the best way to select genuine altcoin cause ones need to put the coin utility, concept, team capacity and community support into consideration before invest into altcoin. Check out
KARATCOIN so you can understand what I mean.