Which camera backpack to choose?

Hey guys, it's my first post here.
So yea, its a newbie.

For me, i'm very ignorant about camera bags even after many rounds of research especially when they all look alike to me.
By the way, i'm from singapore, nice to meet you all here.

So yea, back to topic, my equipments are:
Canon EOS 550D/T2i
EF-S 18-55mm Kit
EF 50mm f1.8 II
EF 70-200 f4L IS USM
Not yet:EF 24-70 f2.8 USM (Soon going to have)
Not yet:Sigma APO 150-500mm f/5-6.3 DG OS HSM (After 24-70mm)
1 Flash (Nissin di 622 mk II)
Remote and accessories
Tripod

I wanted a backpack so its easier to carry compare to sling one.
And i have wanted it to be vanguards or lowepro (cuz it's easier to find as most shop have it) and i find their bag quite good.
i want a backpack that can hang my tripod too so i don't have to carry it in hand.

Any suggestion?

I have a Kata UL-BG-255 and love it! - this is assuming you wish to take a laptop as well. You might also check out the Kata UL-B-222 (it's a little bit smaller than the 255).

Kata models are pretty good. I have a Lowepro Pro Runner 350AW which can fit all the things you have and can hold the tripod on the back with straps.

Thanks for all the suggestion.. i will take all into consideration..
cheers!

I have a Lowepro Flipside 300 that can fit a 7D or 5D3, 24-105L, 100-400L, and one other lens (10-22mm or 135L, in my case), plus a 430EX Flash.

The Sigma 150-500 might be a stretch, as the 100-400L barely fits. The Flipside 400 would give you more room. I also just bought a Flipside 500 for when I want to carry two cameras.