I've spent the last several weeks looking for some potential alternatives to Opera 12. Like many of the opinions expressed here, I too have been quite disappointed with the new Opera and have lost trust with the developers and the company. I understand the reasons why Opera wanted to make a switch from Presto, but to release an unfinished browser on the community is unacceptable. It is also not acceptable to ask unsatisfied users to "hold tight" to Opera 12 while clearly stating that the new Opera will not have the features of the old one. I would argue that most users who switched to Opera did so for its uniqueness and functionality. I don't understand how closing the door on the <2% of users who use Opera to imitate Google Chrome, which is backed by more developers, more users, and far more resources, makes any business sense.
In any case, I thought I'd share my experience, since I am sure many others are wondering where to go from Opera 12. I personally have switched to SeaMonkey for now and find this works quite well. Other options I have tried or researched with some pros and cons are mentioned below. Please keep in mind that I use Opera Mail and so I was looking for both a browser and mail client alternative. The reason from switching away from Opera Mail is again due to a lack of trust with the development team. Especially now that Opera Mail is a separate program and is not to be reintegrated with the Opera browser, I highly doubt that it will get much attention by the Opera team.
SeaMonkey
Pros:
- The only other web browser/email suite I am aware of
- Using this as both a browser/email client will use less system resources than using two separate programs
- Handles many open tabs far more efficiently than Opera 12
- Highly customizable, similar to earlier versions of Firefox
- Can gain many Opera 12 functions using Add Ons
- Some Add Ons offer superior functionality to what was offered in Opera 12 (particularly Adblock Plus and Flashgot in my case)
- Uses Mozilla source code which allows some Firefox extensions to be used in SeaMonkey (may involve some trial/error)
- Firefox updates pushes SeaMonkey development due to the shared code
- Open Source and community driven development which makes it less likely that users will experience something like what just happened with Opera
- Has been around for some time, officially SeaMonkey since 2006, was the Mozilla Application Suite prior to that, browser is descended from Netscape
- Email client more friendly to use with IMAP Gmail than Opera Mail
- Email client is similar to Thunderbird. Although I haven't tried it yet, it seems like exporting emails and contacts to Thunderbird would be very easy.
- Can easily import your Opera Mail and Opera Bookmarks
- Bookmarks!!!!!!!!!!!!!
Cons:
- No mouse gestures. I haven't found a SeaMonkey Add On to implement this, but a Firefox one might exist
- No speed dial
- Interface feels a bit outdated (but you can use Firefox themes)
- I had to manually cut and paste my contacts from Opera Mail into SeaMonkey as there is no easy way to export Opera contacts to use with SeaMonkey (or Thunderbird for that matter)
Firefox and Thunderbird
Pros:
- Review by TomsHardware rates Firefox as the top browser
- Firefox rated as the most "trusted" browser by users
- Handles many open tabs far more efficiently than Opera 12
- Highly customizable
- Many Add Ons, I personally can regain all the functionality I regularly used in Opera 12
- As with SeaMonkey some Add Ons offer superior functionality in certain cases to Opera 12
- Open Source and community driven development
- I found Thunderbird more friendly to use with IMAP Gmail than Opera Mail
- Add Ons to better integrate Firefox with Thunderbird
- Can easily import your Opera Mail and Opera Bookmarks
- Mouse Gestures
- Speed Dial Add On
- Bookmarks!!!!!!! Oh wait, all other browsers have bookmarks. I'd apologize for the sarcasm, but you must admit releasing a browser without this feature is absurd
Cons:
- Community complaints of recent changes making the new Firefox look too much like Chrome. I personally did not find this to be an issue.
- Two separate programs increase the memory usage, not quite double that of SeaMonkey, but close
- In mid 2012, Mozilla announced development focus away from Thunderbird and planned to keep further development primarily community driven. As far as I can tell, it continues to be updated.
- Not easy to import Opera Mail contacts into Thunderbird
eM Client (email client only, can use with your preferred browser as you can with Thunderbird)
Pros:
- Unparalleled synchronization with Gmail, Calendar, Contacts etc.
- Free for personal use, limit of 2 accounts
- Full feature set similar to Microsoft Outlook
Cons:
- Numerous reports of crashes and data loss
- Due to the bugs/problems, generally below average user rating
- Not Open Source like Thunderbird/SeaMonkey
Hope this helps. Please add any other suggestions to this post for potential alternatives.