ETF

So I have sold half of my cryptocurrencies and looking to buy etfs. I know about FTEC. Apart from this, are there are other good tech etfs with low expense ratio? Or are their better ETFs then this with slightly high expense ratio? What else should I look before buying an etf? Any other sector I should look at? I am still young so risk apetite is more and hence not going to s&p at this time. Any help would be appreciated. My brokerage account is in fidelity. I am looking to buy inside 401k account actually.