In my opinion, you the market cap is a good indicator, and only this.

Be careful with coins like Tron, Cardano, Doge, etc... If you are looking for long-term investment they are not good coins. They don't have nothing different or unique, than others already have.

Look for innovative coins, like Waves, Onion, etc... These kind of coins have a huge potencial for the future.

However if you want only sort profit/daily trading, every coin may be good.