leafpad.... is good only for VERY basic usage....
qalculator is quite good
pacmanfm I don't like it.... because if you run as minimalistish desktop as mine, there seams to be no way to configure witch apps configure which apps
I used to like
x11-fm/gentoo - very configurable file manager... it seamed already to be gone, but now they started to develop it further (now gkt2 only.. woot). The only think that in 2-3 years, that I haven't been using file managers.... file managers now seam to slow me down. I do much more and much faster in terminals
I might use
www/opera if it could build with QT4... It used to be my favorite web browser
When you browser large ftp directories. I suggest you use text based browser, they are much faster for this.... I like
www/lynx,
www/elinks and
www/links
I have tried every FM and almost all pic viewers in ports

Also I've tried majority of calculators and players.
I like gpicview, because it's very basic pic viewer, almost entire space is dedicated to display picture....
About epdfview.... it ok, but xpdf is better... I've seen some pdf's that gpicview can't render corectly.... xpdf renders them better (still not perfect). I hate xpdf open dialog... it just ****s
Lately I proffer QT apps over GTK2
Actually since last time I tried KDE4.3 something is bugging me to start using it.... At some point I don't like it (Start menu ***), also I don't like that I can't see end of
$ top
+ extra cpu usage.... but it looks very appealing (and it has some features that my custom desktop miss)