Just a warning, this is extremely picture heavy. If there are any additional comparisons please leave your request in the comments. Without further ado…
Essie Find Me An Oasis vs Sinful Colors Tidal Wave vs Lancome Simply Aqua
SC is slightly darker and bluer
Essie is the most white based and also the most opaque
Lancome has a slight greying-purple toned base
All have similar thin jelly like formulas but I prefer the Essie most for color and formula.
China Glaze What A Pansy vs Sinful Colors Lavander (their spelling, not mine)
ChG is on my middle and pinky, SC is on my ring and pointer. SC is a true creme, much more opaque formula. Also SC is much grayer and also has a slightly blue base.
China Glaze Lotus Begin vs Sinful Colors Beverly Hills
On my skin tone I much prefer the ChG even though the SC has a better formula.
China Glaze Lotus Begin vs China Glaze In A Lily Bit
China Glaze In A Lily Bit vs China Glaze Sweet Hook vs Sally Hansen Lacey Lilac vs L'oreal Sweet
Lily has absolutely the worst formula, it is so close in color to Sweet Hook, I don't understand why China Glaze screwed up the formula so badly when they have done it so fantastically before. Sweet Hook is slightly more gray based while Lily is more pink based.
SH is much more blue based and looks like a true purple compared to the other much pinker options.
L'oreal is far whiter and paler.
No dupes here, though both China Glaze polishes are close enough that you probably don't need both.
All China Glaze At Vase Value vs For Audrey vs Too Yacht To Handle vs Kinetic Candy
ring middle pinky pointer
China Glaze At Vase Value vs Maybelline Mint Mist vs OPI Gargantuan Green Grape (blue version)
OPI is much lighter and a jelly like formula while ChG is a true creme. Mint Mist is very similar, but isn't neon and is slightly more green.
Again, if there are any other comparisons you would like to see please request them in the comments. I will do my best to swatch your requests.