You served us well for many years, beating all competition, and it shows in your old age and scars of development. To bring back the freshness and speed of the old days, with a modern and powerfully multitalented browser, we say:

Welcome SeaMonkey 2.0!

Why?
Here are some reasons why SeaMonkey is better than Firefox:

1) Uses only 56MB on google.com, while Firefox uses 82MB

2) Faster than Firefox 3.5.5. Firefox 2.0 was always faster, and SeaMonkey is based on that.

3) Firefox 3 introduced frequent crashing, especially when you close and reopen it quickly, but also randomly when you open it.

4) Firefox 3 hangs up quite often, taking all CPU load, even on simple web pages with only one instance running.

5) SeaMonkey has also e-mail, graphical HTML editor, and IRC built-in. Still it uses less memory than Firefox.

6) Firefox takes sometimes 10-20 seconds to open certain Ajax based chats on forums.

7) SeaMonkey runs on Windows, Mac, Linux (just like Firefox).

8) It has less security holes, and is less attacked (since most attackers focus on IE and Firefox).

9) Firefox takes over 30 seconds on first time to open when I start my PC. SeaMonkey takes 7 seconds.

10) It has collapsible toolbars, like Netscape had. It has collapsible and resizable sidebars, just like Notes 8 has!

11) It has profile switching! This is very useful for web developers, as they don't need to use different browsers for each user, or close all browser windows to switch a user.

12) It has theme switching.

13) It has a site navigation bar.

14) It scores 93/100 on Acid3 test (same as Firefox 3.5.5, but IE8 gets only 20/100, and IE9 gets 32/100): http://acid3.acidtests.org

15) It has no home button (yes, that's a benefit, read on...). I was at first confused and thought, that cannot be, it's a useful button! But then I thought about it more, what is it actually? It's just a clickable item in the browser. So I figured, I can just as well put my new home button as first link in my bookmarks sidebar (F9, not Ctrl-B like in Firefox). Then I have all clickable sites in the same place, and don't need to move far distances with the mouse to the home button. Play it in your mind, how you navigate to the links and to a home button near the navigation buttons. It suddenly feels very unpleasant to have to use links in different locations. It feels like I have to switch to a different thinking routine, and that's stressing.

16) It has probably a lot more benefits over Firefox, but I just started using it an hour ago :)

17) Pressing Ctrl-U gives you a adhoc-realtime source display of a web page. You can update the source by refreshing the window. You can't do that with any other browser.

It's not so far fetched for (ex-)Firefox lovers, as Mozilla features them side by side, although you might notice that they say that the all-in-one Mozilla suite is no more, so what to choose? (the choices are alphabetically sorted, to avoid any bias):
http://www.mozilla.org/projects/browsers.html