I am an Ethereum fan and I also invest in Ethereum, but I saw Polkadot price increase very high and now Polkadot is in the top 5 on coinmarketcap, so in your opinion in the next 7 days, which price will increase very high? Ethereum or Polkadot?
if I personally would definitely choose Ethereum

Well, the two coin are better for holding than just holding one. Personally, i will choose ethereum becasue it's still undervalued though including the polkadot which hit the crypto market recently. Currently am holding these two coin becasue they compliment each other, though Polkadot still early in the market and may see something big in future.