Steve Vai has talked about his vibrato before being a hybrid of classical vibrato (nylon strings and fretless instruments) and the more extreme vibrato. Circular only really benefits chords and otherwise is just something he decided to do.
If you want to get better/sound better you will first have to discover what you are doing badly - critiquing your improvisation or having someone else do it is a huge thing because after a minute or so it's likely all the bad stuff starts coming out haha (in my case anyway). Posting videos on Steemit has both motivated and mortified me, I mean - I can barely play the songs I have written and recorded because I have never practiced them for performance... it was scary to actually understand that I'm not that good overall but it was also an important lesson that has cemented in my mind the importance of schedule and organisation when it comes to practice. You can watch all the videos in the world but the reality is as a guitar player you have to choose a path and stick to it if you want to achieve excellence - Vai/Satch et al are only as good as they are because they embraced certain aspects of playing and rolled with it. They haven't really done anything new in the last 30 years in terms of technique (said extremely loosely and only to highlight a point) - how can we as occasional players be perfect across all the styles/techniques when only a few extremely dedicated people even approach that level (Guthrie etc). Be happy with your technique - weed out the bad things you do or focu on them to improve the way you do them, study phrasing by playing the melody lines to songs (I have been working on Arms of the Angel, simple notes but a whole world of inflection and dynamics) and most importantly understand that you is what you is and that's perfectly fine (TLDR: Embrace your idiosyncrasies)