i think none of them
because people not in crypto ever before will most probably never hear about any of the altcoins. and if they want to choose they are going to choose the biggest, and oldest technology not just anything with small market that was created new.
I tend to agree with this right here. Most people have no clue what bitcoin really is, much less that there are hundreds of these other coins trying to gain their share of the market. And even if they knew about the altcoins, making an informed decision as to which would be worth owning...yeah, no. Not happening. For lay people, it's bitcoin or nothing.
I found about Gridcoin first, then had to learn about Bitcoin. Since Bitcoin is the default conversion coin on exchanges. After that I got into Diamondcoin, Peercoin, Unobtanium, Namecoin and Dogecoin. In that order :-)