What microphone has the least ability to pick up transients?
I want to be flattered.
Show no warts.
It depends what kind of warts you are trying to hide, how big they are and where they are. And, you know, one person's warts might be someone else's "character" for all I know.
Technical flaws in your singing (and not saying there are any) are not going to be fixed by a microphone, but a vocal coach. Poor mic technique and problems with recording space, can be helped by choice of mic, and then just some YT videos, if a coach is out of the question. That's why I like plain cardioid mics for myself and most anyone else I might record, since even experienced singers are generally going to sound good on good cardioid mic.
What's wrong with your basic SM58, for instance? And I'm guessing you tried more broadcast type mics like the RE20 and SM7b? The MD441-U is something I'd like to hear sometime, but it's way too spendy for my wallet, plus it's supercardioid, which I've decided not to use.
I've found that condensers are nice, but they do pick up a lot of detail that it sounds like you want to avoid. But, really, good mics, with some degree of variance, pick up the same things, but in varying degrees over their frequency response and polar pattern, and the source's distance and angle to the diaphragm. What you end up with can be a little or a lot of work to fit into the mix, but it's still going to sound like the source if you recorded it well.
The only thing I don't have experience with is a ribbon, and that's something I'm curious to try, as well, but for me, the SM58 is adequate, with a little bit of taming of sibilance from that frequency bump most mics aimed at live use have.