That depends on your budget for them and what your sonic preferences are. The IEMs that I usually have connected are the Moondrop Aria, a great set of IEMs for the price.
If you want to go cheaper, take a look at the Ultra Cheap IEM thread: The Ultra Cheap IEM Thread
There are many reviews of budget options in there.
If you share a budget and sound preference, I’m sure you will get a bunch of recommendations.
One thing to consider is that the MW200 comes in two different versions, one with 2pin connectors and the other with MMCX, depending on which IEMs you decide to go with, you should choose one or the other.
My review of the MW200 is here: Shanling Audio - Official Thread - #9 by SenyorC