Regarding compatibility (or rendering quality), I think PDFium is the winner. It has a good renderer (from Foxit¹). When I open this PDF² with pdf.js (Firefox 32), an image on page 6 is missing. PDFium (Opera 25/Chrome 38) renders the PDF correctly.
I've fed some black list of ad/counter urls to my firewall, so basically, it's the firewall that does most of the work for me. Don't know if you can afford running a firewall on your laptop, though. The only thing I still use AdBlock for is the nasty inline ads, embedded right into html like, img src="data:image/gif;base64,XXXXX". I guess it can be done by a simple css hack.
s there just a file (or two) I can copy from one computer to another so that I don't have to enter in all my labels and email account settings, and set all my preferences when I get to another computer?
Program Files folder: "C:\Program Files (x86)\Opera Mail\operamail.exe"
Roaming profile folder for that install: "C:\Users\user\AppData\Roaming\Opera Mail\Opera Mail"
Local profile folder for that install: "C:\Users\user\AppData\Local\Opera Mail\Opera Mail"
, to move an Opera Mail profile to a new computer:
First, move the Roaming and Local profile folders to the same spots on the new computer.
In operaprefs.ini in the roaming profile folder, remove any line that has a path in it so that Opera uses the default path for that setting.
Download the Opera Mail installer and install it to "C:\Program Files (x86)\Opera Mail".
Then, it'll be like the Opera Mail profile was always there on the new computer. All your settings, labels and everything will be in tact.
operaprefs.ini, wand.dat and contacts.adr go along with the mail folder. That's why you should just move the whole profile over. But, if you just move those 4 things over in the spots on the new compute and install Opera Mail to the same spot it was installed at on the older computer, you'll be good to go.