I think web developers are 50/50 when it comes to whether you should use a framework or not. Some agree with their use, others don't. My opinion is that using a framework is fine but add your own twists here and there. By this I mean style elements differently etc. Bootstrap is a very popular framework but this means there's a great abundance of support and documentation to help your learning of its use. Frameworks in themselves may actually help you learn more skills if you take the time to analyze the code. If your going to use a framework though, I would definitely say use Bootstrap, at least to get used to using one.

As for the using other peoples code argument, I definitely agree with the no use policy but frameworks are different because they have been designed specifically for use by other developers and are licensed for this purpose.

I would recommend using a framework for basic things such as layouts using the grid systems etc but don't rely solely on them because you might get lazy.

Good Luck

I find bootstrap more useful for quick prototyping of user interfaces for web-applications than anything. It's not as useful (to me) for making customer facing websites, unless you're really itching to get a prototype out, or need to spend a lot of time on backend details like database structures, user settings, and other technical details. We also use it internally for private UIs, where we don't care how unique the design is, as long as it looks decent and functions well.

One thing is for sure, if you're doing HTML and CSS regularly, you NEED to be able to make a design happen from start to finish, framework or not. Frameworks, if you choose to use them, should be tools, not crutches. If you're not able to do it from the beginning without the framework, don't bother.

Bootstrap's currently one of the best frameworks to use. It's optimized for performance too. I'd go with Bootstrap for sure.

Your thinking is correct that frameworks would speed up what you're trying to do. Just that, each framework has its own way of doing things, has its own, well, ETHOS (the fundamental character or spirit of a culture; the underlying sentiment that informs the beliefs, customs, or practices of a group or society; dominant assumptions of a people or period). So, bootstrap users would have their own way of doing things with css based on certain concepts. Blueprint and 960.gs would have their own, as well.

For some frameworks, you might find that the grid IS the framework, such as 960. You might also find that a grid system is most helpful in trying to lay out your column alignments. You can use Bootstrap WITHOUT using its grids, but if you try to lay out a page of some complexity (try manually laying out a 3 sectioned page with 3 columns, then one column + sidebar on golden mean, then five columns for these three sections with sporadic banner ads and mini banner ads scattered throughout and getting all of that to align in a visually pleasing way), then you might discover the hard way what a built in grid system is for. I could be wrong, but my best guess is that you haven't really spent any significant time with any framework at all, and you're just saying that any grid system is limiting based on your conceptual thinking.

The best way to go about choosing any framework is to test drive it. Because what's important is if your chosen framework can work with how YOU work. And finding that out is best undertaken by yourself, since you alone know how you best work and go about your design.

But then again, if you "dislike using other's code", then maybe any framework isn't for you at all. Taking Bootstrap from zero to where it is now, I'd reckon some few hundred (or most likely thousand) man hours have gone into that to evolve it to where it is now. If you dislike using other people's code that much -- and if you're that proud that you'd be willing to burn a few thousand hours of your own time to get to use a css framework you can surely rely on -- then build your own.