Well if you ask me if what is the safest and most reliable altcoin for me is that all I could say is that I would still choose bitcoin than any altcoins or any crypto currency out there because nowadays almost all of the crypto currency out there are just fake ready to be abandon by its developers as soon they got money from its investors and there's no other safest and most reliable rather than bitcoin.
Quiet true. But one can also choose ethereum next to bitcoin. It has already proven its credibility over the past years. Some potential altcoins are good but it is quiet hard to determine because of many scam coins. To be safe especially for beginners, bitcoin is a good choice. Though it is quite expensive even it's price has been dropping.