My wife asked me which one I like more

It's a trap!

As a female, I can see why she asked. They're clearly different shades

Let's vote for a color! ¯\_(ツ)_/¯
( upvote the one you like most )

I'd say the third from the left. It's the most used so probably the one she likes most. Safest answer.

I'd sit her down, wipe a little tear from my eye and say, "this is really hard to talk about and I've never really told any one." (Pause so she can say, "honey it's me you can tell me anything.") and then say, "I am color blind." If that doesn't work, then tell her she looks great in any color and pick one at random.

They probably all look transparent on the nails

I like the last one on the right

Tell her you can't see the difference because most men have some degree of partial color blindness leading to difficulty distinguishing between specific shades of the same color. Some scientists say this is an evolutionary result of mother primates gathering food and distinguishing between healthy and poisonous fruits.

None. They'll all basically be invisible on nails

She clearly likes the third one so why ask.

I'm a man and I can see the difference in all those shades.

I'm a girl and the difference is
-| |- that much.

UHHH...NUMBER 78

I like the one on the right.

What a waste of money, Essie polishes are sort of expensive
They're all nearly the same color

Guys, here's the secret. It will simultaneously blow her mind and maybe shut her up:
.
Secretly study up on the core of fashion. Colors, composition, coordination, expected dress levels of the event, seasons, time of day and so on.
Don't let on about it, then when you get this question sprung on you, break it down. Deconstruct it in tooth pullingly agonizing detail:
Where are you wearing it?
With what?
What kind of event?
What is the event for?
Time of year? Time of day?
Work, semi casual or formal?
.
One of two things could happen. You will either know what to say AND that opinion will be trusted, rather than casually tossed asside, OR she'll stop asking because an info dump of that magnitude is weird to her coming from a guy.

But.... They are all the same.... well, i am color blind

What the heck.. They are all the pretty much the same

The 4th cream from the left, obviously.

If you didn't pick barefoot and topless, I'd be upset