The term “best” depends on reliability, resolution, stability, cost, available channels, VOD. You can read IPTV Adviser article about the best iptv providers review.
So far I tried these IPTV services:
IPTVtune: Content Quality is excellent, Never had buffering issues or any problems, I was very satisfied with the VOD offerings though.
IPTVGEO: Image quality is very good and zapping is very fast, Great experience with customer support. They answer fast, friendly and offer a high service level, really nice to have all the UK, USA channels available.
IPTVspring: Good quality (Most videos seem to be in HD, but no 4k channels) I was very satisfied with the VOD offerings though.
That was some of the IPTV services that I tried in 2019–2020, currently, I’m using IPTVtune, think is the best IPTV service provider for 2020, But please what may work for me won’t necessarily work your side, I recommend trialling several services and see what works best for you.

how much do these cost. and what kind of connection do you use with your ISP.