I reckon the best cryptocoins to buy as long term investments during bear markets might be those exchange utility tokens like FTT and BNB. Exchanges always collect revenue in bull and bear markets and this gives the tokens some fundamental backing. Also, the utility of those tokens in their corresponding exchanges create a demand for them.
Also, choosing a coin or token from this list of institutional portfolios in the cryptospace might be helpful.
XET is looking good, was listed on MEXC and BitMart last month XfiniteOfficial has some great partnerships, September was a productive month for them This is The World's First Entertainment Ecosystem On Algorand Check them out https://coinmarketcap.com/currencies/xfinite-entertainment-token/