Decent & Steady Money Makers?

In GMS, the only way to make any useful amounts of mesos is either by using NX or playing the market. Hackers and exploiters have made any farming/bossing enterprise useless in that regard. As an example, some time before Big Bang I managed to get over 4 billion mesos from a single solo HT run (2 MW30). Now you would not even make 100m without using NX on scissors.
KMS is probably a bit more forgiving though.

EDIT: This does not include any events and what you can earn by those, since that is hardly to be viewed as steady.