Aside from Bowser Jr.,Yoshi,Wario and maybe R.O.B. as my mains,I think I would say I'm decent with Bowser,Sonic and Lucas.
I typically find Bowser to be a character that's put aside alot of times when compared to other kings like Ganondorf and King Dedede,and since I main his boy,than why not the big man himself?Not only does he KO fast when in good use,but he also has great speed for his class,most attacks with medium or long range,and generally feels satisfying to pull a strong finishing move on your opponent with him.Especially that charged Smash.
I first thought Sonic would be too much for me,but later as I learned more of what to do with him,he becomed one of my side-men.Essentialy,once you learn how to battle around your opponent with Sonic,the stage is pretty much your domain.
I've trained a bit with Lucas in Brawl to have a preview of what he would play like in Smash 4,and he feels better here,if because he controls better with lots of improvements.He's quick,covers a lot of the stage's area when he's put to good use,and not to mention his ridiculous knockback for a brand majority of his attacks.Similar to Sonic,I would say the stage is your home territory if you use him well with his knockback disposals at hand.