Both are good choices but the demand right now is to build own miners or buy mining hardware how much honestly your budget for investment. and  maybe you can afford to buy your own mining rigs or bitcoin mining tools.
But if you are just wanted to hold and sell both altcoin and bitcoin could be  good choice but the price of bitcoin is really high today and  we don't know if the price will continue to increase but if you can hold it for a long time expect that you can make profit in the future.. in altcoin you need to choose good altcoin to make profit mostly top 20 in coinmarketcap are good altcoin to hold and sell that can gives you good profit..  so it will depends in you how you can scaling your investment to make a big profit in the future..