To be honest, I think flossing is more important than brushing. I brush once a day before bed (sometimes in the morning after a heavy night out) but I floss after every meal.
Speaking from experience (over three years with the f*ing things), it's a long and painful journey to move a tooth that distance with braces. The other problem with having a tooth pulled is, well, imagine each tooth is plugged into a socket in your jaw. When a tooth is pulled, its socket remains, but it squashes down as the other teeth shuffle about. Think about that - your skull/jaw is changing shape, and your face with it. Just look at any old person with dentures
This is also one good reason in favour of implants.
By the sounds of it you need a second opinion, and going by what you've said I wouldn't bother with this dentist any longer if I were you. Go and see an Orthodontist, they specialise in the kind of work you're after, and they are what dentists want to be when they grow up. They may cost more, but you get what you pay for.
Now, as to your original question, in your position I would go for the root canal.
I've had my back top molars pulled, because one was crumbling apart and the other one could have been saved, but would have been very costly. Getting them pulled was a no-brainer for me as my top wisdoms are coming in straight and will naturally slot in where the molars were. Because your case is the second molar, that's a tooth worth saving in my opinion. You chew with your molars, and a big gap between your first and third molars, or pre-molars and back molars depending on your teeth, would be weird (think: food vs your exposed gum)
Have you had an x-ray? Do you know how your wisdoms are coming in? If not, I seriously recommend it. For interest's sake, here's an xray of mine from about 7 years ago, before I had my molars pulled. You can see that three of my wisdoms are good, one is going to impact (*sigh*), and you can also see the metal-work (pins in my false tooth and a post-braces wire). Having this x-ray has helped to guide my dental decisions, I'm saving up now to get the false tooth replaced with an implant
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