I used both. I had a terrible time with llama, and did not realise it until I used ollama.

I owned an RTX2070, and followed the llama instructions to make sure it was compiling with GPU enabled. I then hand-tweaked settings (numgpulayers) to try to make it offload as much as possible to the GPU. I verified that it was using a good chunk of my GPU ram (via nvidia-smi), and confirmed that with-gpu was faster than cpu-only. It was still pretty slow, and influenced my decision to upgrade to an RTX3070. It was faster, but still pretty meh...

The first time I used ollama, everything just worked straight out of the box, with one command and zero configuration. It was lightning fast. Honestly if I'd had ollama earlier, I probably wouldn't have felt the need to upgrade GPU.