If you are still in the market for a mic, see if you can demo the AT 2035....It's the upgraded version of the AT 2020 and addresses all the issues you mention: It's thicker, creamier, with a smoother top end. It works well with most vocals & string instruments (and drums).
Arguably, the 'best value' all round condenser mic you can buy.
to be accurate, the 2035 is a LDC, the 2020 is a SDC or arguably an MDC. they are very different mics imho and have different uses. for example, 2020 doesn't work so hot on vocals imho (although some sdcs do), and the 2035 DOES work on vocals.
anyhow, for ribbons, yes most are the same. there are short ribbon motor designs and long ribbon motor designs, you want long motor (1.8" or 2" ribbon for example).
apex 205, shinybox, certain mxls and so on all fit the bill fine.
oh by the way, I record classical cello and string quartet and my own classical violin work professionally using stock apex 205s very often. sometimes I used slightly modified apex 205s. but I rarely use anything other than apex 205s. they are something like $120 mics. amazing for classical strings, also great on brass, certain vocals, amazing on classical piano, and really nice on drum overheads for a warmer sound as well imho. So many uses. So much thicker low mids than most other mics in thsi price range. I paid big bucks (>$1000) to buy a lauten clarion which has a ribbon-like lower midrange but a condensor-like high frequency extension. Amazing mic. but for $120 I've bought MANY apex 205s over the years and use them all the time for professional recording of all styles of music.
I'm a producer, mix engineer, session player, arranger, and so on. I make money at this and have for a long long time. For me, if you want richness, you can't do better than the affordable long motor ribbon mics available these days. apex aren't the only ones, but they're easily available to me at local stores and cheap and typically reliable. sometimes you buy one that has a borked ribbon, but mostly they're very good at least in the store I buy from. They do have poor quality control though... so it's a minor gamble to buy one unless you can test it first to make sure it sounds good and doesn't make any strange noises when turned on it's side or anything.
by the way, from a fair bit of testing I have found that the cheaper smaller bodied apex 205 is somewhat better than the larger apex 210. same ribbon motor, ought to sound the same, but 210s ahve lots of body/grille ring and less high frequency output and really sound less good on vocals imho. nice looking due to sheer size, but not worth it imho. this is likely why most modded ribbons based on these mics use the smaller 205 variant rather than the larger and pricier 210 version.
