Some comments from @sipa in #12702.

___

Yes, I think `importmulti` is superior in every way, except:
* Slightly less convenient to use (it requires redundant information, as you have to explicitly state what you want to import, and then give the keys/... to enable that).
* ~Doesn't support P2SH-P2WPKH yet~. Added in #14454

The latter can be fixed by just adding support for that case. The former can be improved by adding 'default' cases (e.g. if you prove a WIF private key, it can permit omitting the address, ...).

{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() > 0)
        throw std::runtime_error(
            "abortrescan\n"
            "\nStops current wallet rescan triggered by an RPC call, e.g. by an importprivkey call.\n"
            "\nExamples:\n"
            "\nImport a private key\n"
            + HelpExampleCli("importprivkey", "\"mykey\"") +
            "\nAbort the running wallet rescan\n"
            + HelpExampleCli("abortrescan", "") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("abortrescan", "")
        );
    if (!pwallet->IsScanning() || pwallet->IsAbortingRescan()) return false;
    pwallet->AbortRescan();
    return true;
}
static void ImportAddress(CWallet*, const CTxDestination& dest, const std::string& strLabel);
static void ImportScript(CWallet* const pwallet, const CScript& script, const std::string& strLabel, bool isRedeemScript) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)