I can't imagine finer medium format combination than a tabular grain 100 speed film.
We haven't been offered a tabular grain 50 speed or 25 speed film so I don't know how you can do much better.
I'd experiment at least a bit with same film but 4x5 or 8x10 see if that is more satisfying.
Otherwise take some of the fine suggestions here.
Your example shows adequate shadow detail without evidence that you rated the film at half speed. But I want to point out that for the finest results, I believe you need to absolutely give the minimum exposure that provides shadow detail (instead of the safer "half box speed" technique that guarantees results but with potential for overexposure... which would mean more grain).