Best soundfont for exporting choir practice mp3 ?

TL;DR - both MS Basic vocals and Muse Sounds vocals are bad at articulating, because they all sing "ah", while actual lyrics might be more like "ta-ta-ta". This is especially a problem when several ta-ta-ta in a row have same pitch, and it is very hard to tell them apart.
Looking for replacement.

I am quite new to MS4, but computer-literate.
My goal is to create a nice set of choir practice mp3s for every part so people can simply learn their part at home (>50% of people can't even read rhythm on the scores - we are low-effort choir).
For MOST of our songs we have bought professionally prepared practice mp3s recorded in a studio. Currently I have a song with no practice mp3s, but I have MuseScore4 file.

Muse Sounds Grand Piano is GREAT AT ARTICULATING and almost perfect in everything and everything, except that it cannot hold sustained notes. I think this detail is important for practice for people that cannot read scores.

After wandering around Muse Sounds I have found that Violin 1 (Solo) is both good at articulating (not as great as Grand Piano but ok) because bow strikes provide strong enough "strike" at the beginning of every note, it plays staccato well and also can sustain. Viola (Solo) is also good, while Violoncello (Solo)'s bow work is more heavy and slow, so some short notes barely get articulated. Non-solo versions are generally less articulated. This all would work well, but Muse Sounds versions have limited range, Viola (Solo) flat out refuse to play anything that (apparently) real viola cannot

Now, I don't want to reuse MS Basic instruments, as this would require to change instrument on a score itself (rather than changing a sound in a mixer). As I understand, I just need to find a good enough SoundFont and try it.

My routine is the following:
Open the score as is (5 voices - 5 parts).
Enable Metronome in playback
In the mixer set target part to +12, other parts to -12 to -0 (have to play with it for each part).
Set target part Sound to, say, Muse Score Grand Piano, other parts Sound to MS Basic (let them sing default vocals, they provide some kind of background harmony reference, but I don't care about articulation there, also they are pretty quiet).
Export to MP3.
All this works BRILLIANTLY except for the fact that Grand Piano cannot sustain.

Now, I am brand new to the world of SoundFonts and don't have an idea how to navigate it at all. I don't have anything installed on my PC yet (except for MS Basic, and "Muse Sounds" library).
What I think I need is something like Violin 1 (Solo) or Viola (Solo) from Muse Sounds, but without range limitation (no matter how unreal it is going to sound). I don't need it really to be realistic as Muse Sounds are.