This review pooled 110 randomized trials involving 8,130 cognitively healthy adults aged 60+. Mind-body exercise (tai chi, yoga, qigong) ranked highest for executive function, processing speed and attention. Aerobic exercise ranked highest for global cognition and language, while HIIT ranked highest for memory.
That makes the interesting finding less "which exercise is best?" and more "best for what?"
There are important caveats. Many comparisons in a network meta-analysis like this are indirect, and the attention result had the widest uncertainty. And "mind-body exercise" is a broad category: tai chi, yoga and qigong aren't interchangeable, so this study can't tell us which of them is responsible for the result.