I've just took out my MK2 for a listen.. maybe my preference shifted as now to me (even with thin foams) the bass is too much for me for long listening sessions. with one song though, it is still IM. .. PRESIVE...
my most favorite Willsound now is the PK32 (also my most used earbuds this past month), followed by the MK3. the PK32 is more "bookshelf monitor speaker" correct in tuning for me. the bass has clear fundamental note, the kick drum is snappy and doesn't tail (no boomy-ness at all). the soundstage is more spread out to the side, while the MKs is more spherical and cavernous like listening to cinema sound system. that's why i still choose the MK2 as my movie earbuds. and the most important thing for me is that vocals feels dead centered and special with the PK32. it makes you want to listen to the lyrics without being bloated in the mid frequency.
i got a chance to test some moondrop iems last month, and the PK32 is similarly tuned and can stand toe to toe with moondrop A4(it's 4BA and most expensive flagship) . if i didn't have the PK32 when i auditioned it i might have ended purchasing the A4
mind you, this is an opinion from someone who lately listens extensively to the Etymotic iems that most people would find thin in bass (although from what I've read on the Ety forum, those who have them don't feel the bass lacking)