Return or revert scenarios.

ReturnOrRever.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.4;

contract RevertWithString {
    function buy(uint amount) public payable {
        if (msg.value < amount)
            revert("Not enough Ether provided.");
    }
    // transaction cost	21499 gas 
    // execution cost	295 gas 
}

contract RevertWithRequire {
    function buy(uint amount) public payable {
        require(msg.value >= amount, "Not enough Ether provided.");
    }
    // transaction cost	21499 gas 
    // execution cost	295 gas 
}

contract RevertCustomError {
    error NotEnoughEtherProvided();
    function buy(uint amount) public payable {
        if (msg.value < amount)
            revert NotEnoughEtherProvided();
    }
    // transaction cost	21445 gas 
    // execution cost	241 gas 
}

contract RevertCustomErrorWithData {
    error MyCustomError(string);
    function buy(uint amount) public payable {
        if (msg.value < amount)
            revert MyCustomError("Not enough Ether provided.");
    }
    // transaction cost	21499 gas 
    // execution cost	295 gas 
}

contract JustAGetter {
    function buy(uint amount) public payable returns (string memory) {
        if (msg.value < amount)
            return "Not enough ether provided.";
        return "Enough ether provided.";
    }
    // transaction cost	21756 gas 
    // execution cost	552 gas 
}

contract RevertGetter {
    error MyCustomError(string);
    RevertCustomErrorWithData custom;

    constructor() {
        custom = new RevertCustomErrorWithData();
    }

    function getString(uint256 amount) public payable returns (string memory) {
        try custom.buy(amount) {
            return "This should never run";
        } catch (bytes memory lowLevelData) {
            return string(lowLevelData);
        }
    }

    // transaction cost	21756 gas 
    // execution cost	552 gas 
}