A welcome bonus has many factors, and it enables a different style of play. There really is too much to be considered when asking such a general question. Yes Slotland has the lowest wagering, but lots of other online casinos have 400% bonus with no max cash out as well. Although we can set aside the BS and really cut to the chase here…
In Order of Importance:
Is there a max cash out?
Is the playthrough over 30X or 25X (deposit+bonus)?
Is the bonus cashable, meaning its is not a “phantom bonus”… aka not stcky?
Will the player bet a substantially higher amount per spin, and the bonus is not capped per spin at under $5?
Does the player want to spend a long time at the casino, or do they want to make a quit hit and run?
If the answers are all yes, than that player would probably see a lot of benefit in using welcome bonuses when they make a deposit. Of course, finding one that fits all of these criteria is very difficult, but that the technical answer. In order to catch a new players, describing all of this will not help much… they are still a tremendous tool to give people a taste of the slots and/or games longer, and thus, they have attracted a unbelievable amount of traffic and sign ups over the years. For affiliates, they are a good thing.