Every moment I spend with you is better than the next.

Shakespeare had a banger.

"I was going to challenge you to a battle of wits but I see you are unarmed."

I also like.

"I could agree with you but then we'd both be wrong."

You're really at the top of the bell curve!

You are hard to underestimate.

"See you soon!"

"Not if I see you first"

"That's a surprisingly confident take."

Colbert at Bush's correspondence dinner:

The greatest thing about about this man is that he's steady, you know where he stands. He believes the same thing on Wednesday that he did on Monday... no matter what happened on Tuesday.

You are a testament to the quality of the educational system.

Not directly related, but I've always liked the comeback

I've been called worse by better people

Almost every British insult is like this.

• I admire your courage in wearing that!
• Your personality is unique.
• I'm genuinely impressed by your unconventional approach to social intercourse.
• Your hair is magnificent, does it grow everywhere like that?
• You have such a tremendous, characterful appearance. Ever thought about a career in radio?
• You're really very special, aren't you?

You cured my impostor syndrome, thank you.

This one's not so brainy, but considering the character it was addressed to it was enough - that being one of my favorite lines from the show Firefly: "Well, my days of not taking you seriously are certainly coming to a middle."

Your ratio of words to significance is extremely high

Among everybody here, you have the most potential to learn something.

These kinds of insults just make people sound like redditors.

My the rest of your day be as nice as you are.

You can't be underestimated

"My days of not taking you seriously are certainly coming to a middle."

-Malcom Reynolds, CAPT.

I like how you live your true self even when it’s not appropriate.

I see you are not hindered by the restrictions of logic.

Many of these rely on big words, or are actually pretty obviously insults even if you don't understand.

The real gems are the ones that read like simple english compliments, unless you spend actual effort looking for the insult.

Gotta use a positive tone and smile:

"You're no better than you ought to be!"

https://tvtropes.org/pmwiki/pmwiki.php/Main/StealthInsult

Look up Shakespeare's insults. They're literally classic.

Wisdom has been chasing you, but you are faster!!

A snarky one I heard from a woman to another.

"It's amazing how you can pull off THAT outfit"

Implying poor taste in fashion. I do think delivery is important here.

I don't have a lot of petty female friends but I've certainly encountered them and they are masters of the craft of two faced insults. Especially involving taste and habits.

Don't feel too down, it's not like this project won't be the same without you.

You were so cute when I first met you.

I don't have one in English, but I have some in German for those who understand.

My Granddad had a female coworker that was higher in rank than him. He would always greet her with "Meine Allerwerteste". It's a word play because "Meine Werteste" is equivalent to a very formal version of "my dear". "Aller" is a superlative form, so basically "My very dearest". But "Mein Allerwertester" (so the male form of what he used) means "my ass".

The other one is to use terminology like "Er versucht immer sein Bestes zu geben" ("He always tries to give his best"). In Austria, you are legally allowed to ask for a work testimony from your employer when you are looking for a new job. There is some legislation that prohibits negative speech in these work testimonies so that your employer cannot make you look bad in front of your potential new employer (which makes the whole concept pretty useless, but it is what it is). So to get around that, employers adopted a kind of "secret" code where e.g. "tries to" means "fails to". So you can use the same kind of terminology to deliver something that sounds like a compliment, but for everyone in the know (which is most people by now) it's clear that you deeply offended the person you are talking about.