Nalgene for me too. I use their original lightweight ones, not as light as Platypus or one of the reused water bottles folks use, but the confidence that it's not going to leak after being dropped or leak if I heat a water bottle to warm up my sleeping bag (one of the best "pro tips" ever!).
Not sure why, but Stone glacier made a Nalgene holder that hung in front of your shoulder that I love, but it's been discontinued. They still make one that is a belt holder though.
I use Aqua tabs for purification. I always one Nalgene ready to drink, when one goes dry it gets filled w/ a tab thrown in; when the other one goes dry it it's ready to go—rinse and repeat. I've used filters, they get clogged, I've used UV and had the electronics fail. Always carried tabs as a backup, now that's all I carry
If I'm in water stingy country, I'll throw in a 2 liter Platypus bottle if I need more water (in addition to the two Nalgenes.
Not a very good close up, but you can see the holder I'm talking about by my left shoulder—very handy to grab and put away.