Taking your concerns into account (yes, everybody says that price doesn't matter, but we've seen how the regulators in many different countries have started moving when the price climbed to 19k, haven't they?) I would register in more than one big legit different exchanges.

I don't know which ones are the best taking into account your nationality, as I don't know the regulations there neither, but some international legit ones are bitfinex, kraken, bitstamp... you can also use localbitcoins and/or hodlhodl, and many other platforms like bitcoin.de for german and european traders, but in your country/continent.

Good luck and I hope it goest to 100k so we all can celebrate. I hope I helped.