Yes, it is still a good time to buy some altcoins, since the prices are nowadays affordable. But you must choose the most valuable altcoins which have real potential, and hold them until the price go up again, and avoid the shitcoins and the coins which have low volume of trading.
l do agree with your opinion about that, while the prices are so low, we have to use this chance and collect some altcoins till halving. Altcoins can be profitable in the near future, it is out of the question. As you above said l prefer also to invest in top altcoins, in my humble estimation investing in top altcoins is more valuable than in others.