Boots are probably the most important thing you can have. My recommendation is to go to as many stores as you can and try them all on with different pairs of socks. Go with the one the fits the best. Looks are secondary, but still somewhat important. Even if they fit great but you hate they way they look and vice versa.
I personally love handmand Limmer boots. All leather and take a few miles to wear in. But, once broke in they are the most comfortable boots I have ever worn.
My wife actually wears a pair of Men's 8.5 Garmont Dakota Plus boots.
Second to boots is socks. I highly recommend socks such as Smartwool and Bridgedale. It may seem strange to spend $15 to $20 on socks but it makes all the difference. The more wool the better.
I actually wear ultra thin liners under Smartwool Expedition socks. Wicks extremely well with moisture wicking. Keeps me warm in winter and is not to hot for Moab in the summer.
No matter how tired, cold or sick you are you can keep walking. But, the minute your feet hurt that is is about the end of it.