Dunno about that particular pack, but completely agree with the comments by kbennet.

Of course it's challenging to "buy the pack last" insofar as you likely need some sort of backpack to get the experience with other gear first. If you can't borrow or even possibly rent one to do that, then make a best guess at where you'll ultimately want to be on the spectrum of "traditonal" to "light" to "ultralight" backpacking, in order to better estimate the volume needed, with the large caveat that a lot of things can be strapped or stuffed into mesh pockets external to the pack.

One other caveat with the number of days on a trip is whether you plan your trips to be unresupplied or not, i.e., for a 10-day trip do you carry all 10 days of food at the outset?

Also certainly weather and temperature issues, related to season, altitude, and overall location of your trip --- weather/temperature impacts various gear choices and thus total weight and volume of gear (as well as perhaps water and food carried).

"What brands are best" --- again, depends on where you're shooting for in terms of base weight. If you're looking at the "light" to "ultralight" part of the spectrum, I'd suggest looking at ULA, Gossamer Gear, SixMoonDesigns, Granite Gear. But REI's most recent lightest offerings aren't bad these days.

It also depends on what you personally prioritize when you say "best" --- weight, cost, durability, specific features, personal fit, color, volume, "style" ...

YMMV a lot depending on what you prioritize vs. what someone else might, so I suggest that you be a little leery about any generic recommendations of "best" on any gear item.