Like you, I've stuck with Influx v1, Telegraf and Grafana. My policy is to upgrade only when there are significant reasons to. When I evaluated InfluxDB 2, there were no major reasons for me to switch. Of course, the data ingested in my case is relatively small. YMMV.

I looked at TimescaleDB but at the time there was no easy way to get data from Telegraf to TimescaleDB. Telegraf finally merged code that allows writes to Postgres databases, but it took like 3 years to do that.

Ultimately, I still stuck with InfluxDB v1 because sending data to it via the InfluxDB line protocol is so simple. I have a couple of bash scripts that use awk to transform command output to Influx line protocol and send it to InfluxDB. It's just so simple. I love it.

I love learning about new things, but the InfluxDB v1 keeps working fine so I may not switch from it until something forces me to do it.