I heard about Burency (exchange and blockchain development platform based on middle east) a lot through telegram. They have over 100k members in telegram group. They've recently partnered with huobi. They also featured in a lot of news coverage.
Their native erc20 token BUY are on ICO. Almost 47% are sold. My question is should I invest in buy token

Will it be a good choice

Or any exchange token suggestions other than BNB and HT.
Number of telegram users are not a good indication how good or successful a project will be. Still boils down as how the project has real use case, otherwise if will be just another hype project.
Really hard to give financial advises here, because you know people can make wrong suggestions. As rule of thumb, DYOR (Do Your Own Research).