Cheapest way to buy bitcoin? I’d like to have daily/recurring buy orders if it doesnt cost me too much in the long run.

If I use the strike mobile app in Europe, does this give me a pretty low fees + good spread when I do daily/recurring buy orders? I heard that Kraken Pro might have the best spread + low fees combination, but if the difference isn't too big I'd like to make recurring transactions and not having to worry about it. Also sending it to a cold wallet (trezor) afterwards.