If you like Kagerou, stick with Kagerou. Rule #1 is that all clans are competitive
except Etranger and there is always a way to make a deck work well. What is called the best deck right now is only going to last a couple months at best; even the most long-lived of decks can be stopped dead in their tracks by a skilled fighter who's found a way to use their favorite cards.
You're going to want to know how the game has progressed, so look into the tournament decklists from 2011 to now (if you can read Japanese, the
official website has them all, if you can't I have a perpetually-in-progress
translation/analysis of how the game developed) and Cardgame!!Coalation has
a thread that I try to keep up to date on the current pro scene.
The dub isn't terrible, but I would honestly recommend that you look into watching Crunchyroll's subtitled release to keep up to date on the new cards, and because reading the card names and skills honestly does improve your recognition of them over just hearing them spoken aloud. The dub is also close to 40 episodes behind now, and there are some things that get lost in translation like the origins of Koutei's name, the existence of the Foo Fighters and the foreshadowing to later plot points. Additionally, you'll sometimes be confused by things like no one calling Genocide Jack, Brutal Jack or Blazers Pleasures, Blazer Idols in the real world, because the sub is that much more popular.
In terms of improving your game, real cardfights at actual shops will always be better than online play with CFC (Bushiroad is very nice in that they
keep an ongoing list to help narrow down the hunt.) Cardfight Capital is nice, but the program has issues with its shuffler, can't replicate every skill in the game and won't work as a substitute for real experience.
For a Kagerou cardfighter, the typical route in the Japanese scene and the one expected for the English scene to go toward in February is Dragonic Overlord The End. At the moment, the EN scene has Dragon Monk Goku and Dragonic Lawkeeper as the clan's best in show for the format, but nothing is ever 100% guaranteed in Cardfight. People are always looking into ways to make older decktypes more viable, to tune up new ones and create different combinations, so definitely experiment and see if you gravitate toward a particular strategy.