ZBrush has modeling and texturing tools (+ displacement and normal maps in Z2 - see Z2 preview). To learn about texturing in 1.55b you may want to download the 1.55b demo from www.zbrush.com and view the tutorials which are included with the TextureMaster Zscript.
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ZBrush has an automatic “seam-fixer” which traces and extends the border of the assigned UV coordinates.
Regarding the matter of what program is better, this is a question that is best answered for yourself. Other people can only tell you what works best for them. Check out the feature lists for the programs that you’re interested in and look for the one that will give you most of what you want at the best value. Although I have a hunch you’ll find that ZBrush does indeed give a dynamite value! 