I used a lot of Agfa apx100 and it was superb in Rodinal 1+25 (@ 80 beautiful mid-tones with high micro-contrast) and in D761+1 (less contrasty than Rodinal, but creamy negatives). The Apx now available in the market (new emulsion) it's a very different film from the original Agfa Apx, it shows much more grain than the original one and it seems to be a Kentmere100 rebranded by Agfa-Lupus. Now in Italy Agfa Apx New is more expensive than Kodak tmax (which I consider an overall better film) so I don't use Agfa-Lupus film any more.
Anyway, I'd start with D76 1+1 because it's less grainer than Rodinal, produces excellent negatives with most of the film and it's very hard to beat.