The easiest one is a microcoil with cotton in my opinion. You compress the
coils together this way, so perfectly even spacing is less of an issue. Most use cotton for taste and ease of wicking. I've recently been using Japanese cut cotton pads from Muji. I haven't noticed much different in taste, but I do find it easier to pull apart the amount of cotton I want and less goes to waste. Do not
buy those cotton pads from Amazon. They're charging an arm and a leg. I got mine from Muji itself. $2 something for a bag, plus $5 in shipping. Amazon is selling bags for $11.