Before I retired, I ran a small hosting company/ISP, and had a lot of upstream providers and commercial internet connections. Some of my providers were very good, and some, well, not great.
The best was a company called Level3. Their service was awesome. I had guaranteed 100% bandwidth, and guaranteed low latency.
My residential connection from UIA is better. Their support is amazing. I don't have the guarantees, but that would cost a lot more.