many have presented their own choice of coin that they deemed might reach 1000 times of its initial price however what most people here don't really think about are how much the market capitalisation of the coin gonna grow if the coin ever reached that high like many stated. you just don't expect these altcoin to surpass the market capitalisation of bitcoin.
Indeed, there are still many say Ethereum, LTC or Matic and other top 10 or top 100 coins,
without looking at the important thing you mentioned, yes that is market capitalization,
because the top 10 altcoins or top 100 altcoins will be difficult to reach 100x or even 1000x,
if you want to look for 1000x altcoin, of course you have to look for it at medium cap or low cap because that's where the altcoin gem is.