Many altcoins are shitcoins, if this year is not favourable their price can be worthless and never reach all-time-high again which should be what we should mostly avoid. Do more research.
This is not about trading or short term investment and may exceed a year.
Invest in bitcoin, if the price decrease, invest more. A time is coming when bitcoin will again reach all-time-high. All your investment will never at the time be in vain as you will make profit.
Bitcoin investment is the safest one and will reward you in the long run. However, there are some other coins like eth , cardano and dot which may give better returns as compare to bitcoin. Sometimes shitcoins also give 100x returns. So my piece of advice would be to calculate your total money first which you allocate for the crypto investments. Then with 50% of that money buy bitcoins and with 25% of that money, you can by other good coins from the top 10 list. The remaining 25% of the money can be allocated to shitcoins. This way you will get the maximum returns while minimizing the risks.