Theorically, Falkon, the KDE web browser, is great, better than Chromium, it has integrated features, while Chromium needs extensions:
toggling fullscreen by pointing at the top, Chromium https://chromewebstore.google.com/detai … kikahiffep ,
user style sheet, Chromium e.g. https://chromewebstore.google.com/detai … hkbjmjklng ,
ad block, Chromium https://chromewebstore.google.com/detai … hcphecmpfh ,
user agent manager (e.g. I need a Windows user agent for battlelog.battlefield.com ), Chromium https://chromewebstore.google.com/detai … pkjnoahfmg  .

Also a Chromium's annoyance:
e.g. Falkon I can both navigate without saving history & logins stored (e.g. I log in to github, I close Falkon, I restart it, I'm still logged to github), Chromium no: either normal but history saved, or Incognito but if I close it I lose logins, yes there's Autofill username & password, but logging to github I reneed my smartphone to receive a code by SMS...

The only feature (I found) Chromium has but not Falkon:
New tab to the right, Falkon only Duplicate Tab...

But practically, unfortunately Chromium is better than Falkon, Falkon has:
performance lack https://bugs.kde.org/show_bug.cgi?id=521810 (Firefox: a disaster https://www.vsynctester.com/firefoxisbroken.html , so why I don't talked about that browser),
a bug, blank developer tools https://bugs.kde.org/show_bug.cgi?id=514459 ,
its ad block doesn't work for YouTube video ads https://bugs.kde.org/show_bug.cgi?id=445836 .

Conclusion:
my choice is unfortunately Chromium, I hope Falkon, Chromium based (QtWebEngine), will become better, after a falkon update I test the 3 above.