Am using Opera more because it is having more features than any other browsers also Opera is more customizable. But i want to use other browsers because some of the sites are not displayed properly in Opera because they are designed only for IE or Firefox. In this i havent considered the beta versions of these browsers. You will have to find add-ons for firefox for each facility.
1. Opera
a. Mouse Geastures
b. Feed Reader
c. Widgets
d. Bookmarks
e. Block Advertisement
f. Popup Blocker
g. Download manager
i. Torrent download Support
j. Email Client
k. Crash Recovery
l. Acid Test 2 Passed
m. Themes
n. Voice controlled Browsing
o. Speed Dial
p. Spell check (You need to install Aspell)
q. IRC Chat
2. IE7 with IE7Pro
a. Mouse Geastures
(Missing) b. Feed Reader
(Missing) c. Widgets
d. Bookmarks
e. Block Advertisement
f. Popup Blocker
g. Download manager
(Missing) i. Torrent download Support
(Missing) j. Email Client
k. Crash Recovery
(Missing) l. Acid Test 2 Passed
(partially Missing) m. Themes
(Missing) n. Voice controlled Browsing
(Missing) o. Speed Dial
p. Spell check
(Missing) q. IRC Chat
3. Firefox with Addons
a. Mouse Geastures
b. Feed Reader
c. Widgets
d. Bookmarks
e. Block Advertisement
f. Popup Blocker
g. Download manager
(Missing) i. Torrent download Support
(Missing) j. Email Client (You can get this feature if you use Sea Monkey)
k. Crash Recovery
(Missing) l. Acid Test 2 Passed
m. Themes
(Missing) n. Voice controlled Browsing
o. Speed Dial
p. Spell check
(Missing) q. IRC Chat (You can get this feature if you use Sea Monkey)
you can download Advertisement blocking list from Fanboy's Site