I've had my Mests for about 6 months now and they haven't stopped blowing me away. They aren't perfect tuning-wise for me either, but at the same time they've barely left my ears since I got them lol. I honestly love the smaller, immersive soundstage and slight veil they have but I completely understand why you have issues with it. I think the biggest issue I've found is that any EQ ends up destroying the really special imaging they have.

I haven't actually heard the B2D (I was going to buy it but decided I might as well just go to the top) but I know it has a fairly different tuning. I've seen its detractors describe it as cold/analytical, which is kinda what turned me off from buying it. I could be wrong but I believe the B2D is tuned close to the Harman target (which has pronounced mids) while the Mest has an unusual U-shaped tuning. You might just prefer more forward mids compared to the Mest, I definitely feel that they lack the body and warmth that I love from my HD 6XXs. I unfortunatly haven't heard the Diva either but it seems like I'd like it. I'd also love to hear the Traillii someday as I've heard its the king of mids but there's no way I'd ever pay that much lmao.

If I could give a suggestion, the Cayin RU-6 R2R dongle is absolutely magical with the Mest. I'm not the type of guy who's like bro you need a $1000 special DAC to properly enjoy stuff but the RU-6 made a noticable difference. It sounds more "open" while giving some more body to the mids, but it does take away some of the resolution. You absolutely don't need it but it really completed the Mests for me. Good luck with your search, always happy to see another Mestbro :)