Different quantizations can give you a big speedup if you've had "depressingly slow" issues. Even the slowest ones (that fit in RAM) will run at basically interactive speed, not instant, but also not "email speed". I have a laptop with a 2018 CPU and I'm working with them just fine.
Text generation style instead of chat style is another avenue that makes the feedback time not so annoying for a developer.
at 100ms/token, it's faster than most people type, I think. That's what you might get on an old laptop with a 7B model.
There's a useful leaderboard here to help you pick a model: https://huggingface.co/spaces/HuggingFaceH4/open_llm_leaderb...
It really depends on your task, lots and lots of natural language type tasks give great results, the models seem to have extensive knowledge of many fields. So for some kinds of Q&A bot (technical or not), for copy blurbs, for fiction, game NPCs, etc, the models (especially 13B and up) can be breathtaking, even moreso considering they run on bottom-dollar consumer hardware (I paid $250 for the laptop I'm developing on).
There are of course some things that neither the local LLMs nor GPT4 can do, like create useful OpenSCAD models :)
Things keep getting better, newer quantization methods give you more smarts in the same amount of RAM at basically the same speed -- the models are getting better, there are more permissively licensed ones now.