1 Cor 14 - v2. "no one understands him, but he utters mysteries in the Spirit." This is BAD.
v4. "The one who speaks in a tongue builds up himself." This is also BAD.
v5. "The one who prophesies is greater than the one who speaks in tongues, unless someone interprets," Paul is being polite. Better like a million dollars to 0 and, reading further better like a million in the black to a million in the red.
v9. " if with your tongue you utter speech that is not intelligible, how will anyone know what is said? For you will be speaking into the air." <-- proof that Paul is speaking negatively in verses 2 & 4. He says they are 'talking to God' out of generosity, maybe they are sincere believers, but it's really just wind.
v10. "There are doubtless many different languages in the world, and none is without meaning" <-- Proof that the true gift of tongues were real languages.
NOTE: The word translated 'meaning' here is the word for 'power' same as everyone's favorite quotation about Romans 1:16, "the power" or "meaning" of the gospel. PART OF THE ARGUMENT ABOUT TONGUES IS THEY HAVE SOME MYSTERIOUS 'POWER' AND THE TEXT DIRECTLY SAYS THAT WITHOUT MEANING THEY DO NOT, NOT FOR THE SPEAKER, NOT FOR THE HEARER. And you have to go into 1 Cor 12 to see that gifts are given to the CHURCH, not individuals for 'private use'. What you're describing in 'private use' is trance state / meditation. I have a more thorough treatment in a paper I've written on the subject. tl;dr I'm not condemning your trance / meditation that makes you feel 'connected' and 'spiritual'. Just call it what it is.
v12 "So with yourselves, since you are eager for manifestations of the Spirit" <-- This tells us something about the audience--they're into this stuff and think it's cool. Same as people you find babbling today.
v13 "one who speaks in a tongue should pray that he may interpret" <---ie. don't just go on enjoying it by yourself, as if that were possible. Paul is being generous here but is doubtful God would even give the gift outside of also providing the interpretation.
v14 "For if I pray in a tongue, my spirit prays but my mind is unfruitful." This is BAD. See Romans 8:1-8 just for instance about the mind. No Romans 8:26 is not about tongues. v15 "I will pray with my spirit, but I will pray with my mind also;" When we pray words in our own tongue, with meaning, with power, we are praying with both the spirit AND the mind. He is not talking about two kinds of prayer here. He is talking about real prayer that does both. 'tongues trainers' will tell you to pray until you run out of words, to let it come from the gut, to turn off the mind... yes, this is where glossolalia comes from and I can do it... but it is neither spirit nor mind. It only feels like spirit separately if you embrace the trance state part of it. (awkward without being more thorough...)
v16 "I will sing praise with my spirit, but I will sing with my mind also." <--- Proof of what I just said. No one is singing in babbling, that just doesn't even make sense. It was big on reddit today that even the 'duel of the fates' was a real language, even Nien Nunb's words were a real Kenyan dialect(??) because that babbling is ridiculous. (sorry folks, my paper is more gracious. i knew there were people in the audience who were friends and thought they had the gift of tongues)
v17 "how can anyone in the position of an outsider say “Amen” <-- Paul doesn't believe you're really talking spiritually to God, people. He says no one can say amen to that. Okay, maybe, maybe you are, see v18, but we're not buying it.
more v18, "I thank God that I speak in tongues more than all of you." Someone else here said he spoke them more because he traveled the known world. Nailed it. Yes. No reason at all to think he would be referring to 'privacy' here.
You will say to me then, 'But /u/Odous why does he say in verse 19, "Nevertheless, in church" .. isn't he comparing speaking in the church and speaking in private.' Great question /u/terevos2 etc, NO. He is contrasting speaking in the church and speaking in the mission field. Proof: see above characterization of what it is to pray mindlessly (unfruitful), also the hyperbole in the rest of the verse, "ten thousand words in a tongue" referring to what I believe is the description he got in the report/letter from Corinth about what was going on. It would be unfathomable.
v20, "do not be children in your thinking." Further proof that everything I said was 'bad' above is bad. It's childish.
I've left some other comments here leading into verses 21-25. Will spare that from the monologue for now.