best for what? There are models catered to different things. GPT4 is probably the best general model out there, and the GPT-X thing is probably the best generalized one that you can run locally so far, but if you want something summarized then you would likely do better with one trained or finetuned specifically for summarizing stuff. Training your own set of loras or models is ideal though if you want it to be as capable as possible. Loras are only megabytes in size but can add a good deal of information and formatting so I'd suggest making some for your own purposes and switching them out base don the task at hand.

In terms of the CPU and ram stuff, you probably still wont be running it very fast if you are planning to run it on CPU instead of your graphics card so dont have too high of expectations for speed with it unless you upgrade your GPU to have enough VRAM to run it off of. I believe oobabooga has prebuilt training for loras so you should be able to use that or a google colab for it