I encountered a similar situation where I need to write an xPath for an element shown below:
<img src="webwb/pzspacer.gif!!.gif" class="inactvIcon" data-ctl="["DatePicker"]" style="cursor:pointer;">
I was able to grep the element using below xPath, where I used the backslash to escape the characters [ and ".
What's the problem then? Both xPaths seem functional. On the other hand, a good practice is to simplify it as much as possible, so it's readable for you in the future and for other people. The following xPath seems a bit more readable to me:
//div[@id="opbox-category-tree"]//a[text()="Drukarki i skanery"]
You don't need to write every element on the way ...