With the wide array of altcoins available in the crypto market, how do you choose which one to invest on, which one to buy and which of these altcoins worth holding?
Very simply 
. I read and analyze all available information about the coin. After, if the coin I like, I keep watch for a while. After that I decide to buy this coin, if it seems good to me.If we are talking about top altcoins, I choose only out of sympathy. I think they are all good and will grow in the same proportion with bitcoin. It's a matter of taste in the end.