I'd say it depends on:
- The subject matter. Is this a rapidly changing topic? Will everything you write be out of date in six months? Does it really benefit from being in book form to start with (more on this later).
- Your experience of writing. Are you already confident in your ability to write a long piece? I'm not saying you have to be a fabulous writer before you start, but you should at least have a reasonably established style (in my view, anyway).
- The amount of time you have available. Writing a book is a long, hard slog. When you're in a contract with a publisher, it will be difficult to throw in the towel or take a month's holiday from writing. (Both are feasible, but they won't be pleasant experiences.)
Both forms of writing are certainly fun, and can be quite addictive. Both are very rewarding - seeing your blog's readership (and comment level) is nice, and seeing your name in a book shop is fabulous. Just don't underestimate the amount of work involved.
Oh, and for technical books I wouldn't put too much faith in editors. Copy editors in publishing houses aren't very technical (in my experience) - which means they'll be nervous of changing your text too much, in case they change the meaning. I've worked on a couple of books where I've been listed as a co-author but I've mostly been there to edit the language with an eye for technicalities. Having said that, copy editors do still make a huge difference in polish. Be nice to them :)
As others have said, don't expect much direct financial benefit from either channel. I suspect you'd have to have a very large readership to make as much from a blog as from a book, but you're likely to be working at around minimum wage rates. Very few people write technical books for the money. It can certainly help the rest of your professional life though.
You ought to think about the benefits that books bring, and how relevant they are to your subject matter. Pretty much all the information in my C# book is already available on a blog, for instance, often in even more detail - so why would anyone want to buy a book? I believe it's a matter of organization. If you've got a book in your hands, someone has thought about the best order in which to present the material. They've picked the most important/useful material, too: it can be hard to piece together umpteen blog posts and know whether you're still missing some crucial aspect of a topic. There are the benefits of design, type-setting as well of course, as well as the physical aspects of having a book in your hand - I personally prefer the reading experience of a book over a blog.
You express concerns about technical accuracy: good! Please find a really good tech reviewer who is willing to read your work really carefully. Ideally they should know more about the topic than you. If you're incredibly lucky they'll be able to furnish you with even more information - this is particularly true if you're writing about a particular tech product and they're within the product team. Background information is invaluable, even if you only work a small amount of it into the writing.
Finally, it's unlikely to be an either/or decision: if you do write a book, you should almost certainly blog about the topic as well, if only to drum up readership. You can also use this channel to get feedback on your writing style etc.