Version:           3.2.90 (using KDE 3.2.90 (CVS >= 20040117), compiled sources)
Compiler:          gcc version 3.3.1 (SuSE Linux)
OS:                Linux (i686) release 2.4.21-215-athlon

Related to bug 50284 and my old configuration files...

Nothing but konqueror can be first in "Application Preference Order" (changes can be done but are not persistent, probably related to my ~/.kde/share/config/profilerc see below, since it works on a new user)

~.kde/share/config/profilerc
[text/html - 1]
AllowAsDefault=true
Application=kde-mozilla.desktop
GenericServiceType=Application
Preference=6
ServiceType=text/html

[text/html - 10]
AllowAsDefault=true
Application=katepart.desktop
GenericServiceType=KParts/ReadOnlyPart
Preference=3
ServiceType=text/html

[text/html - 11]
AllowAsDefault=true
Application=kimagemapeditorpart.desktop
GenericServiceType=KParts/ReadOnlyPart
Preference=2
ServiceType=text/html

[text/html - 12]
AllowAsDefault=true
Application=vimpart.desktop
GenericServiceType=KParts/ReadOnlyPart
Preference=1
ServiceType=text/html

[text/html - 2]
AllowAsDefault=true
Application=kde-kfmclient_html.desktop
GenericServiceType=Application
Preference=5
ServiceType=text/html

[text/html - 3]
AllowAsDefault=true
Application=kde-quanta.desktop
GenericServiceType=Application
Preference=4
ServiceType=text/html

[text/html - 4]
AllowAsDefault=true
Application=kde-kimagemapeditor.desktop
GenericServiceType=Application
Preference=3
ServiceType=text/html

[text/html - 5]
AllowAsDefault=true
Application=kde-quanta_be.desktop
GenericServiceType=Application
Preference=2
ServiceType=text/html

[text/html - 6]
AllowAsDefault=true
Application=/home/roger/.local/share/applications/kde/kfmclient_html.
desktop
Preference=0
ServiceType=text/html

[text/html - 7]
AllowAsDefault=true
Application=/home/roger/.local/share/applications/kde/konqbrowser.des
ktop
Preference=0
ServiceType=text/html

[text/html - 8]
AllowAsDefault=true
Application=netscape.desktop
GenericServiceType=Application
Preference=1
ServiceType=text/html

[text/html - 9]
AllowAsDefault=true
Application=khtml.desktop
GenericServiceType=KParts/ReadOnlyPart
Preference=4
ServiceType=text/html

Note that the default konqueror has initialPreference 9
i.e. above all these - I guess that is why it ends up on top... 

Moving konqueror down or moving anything else above will
not help...