As one very simple example, GrapheneOS zeros heap memory on free so the data cannot be leaked after being freed and many use-after-free (UAF) memory corruption bugs are made much harder or impossible to exploit. As another very simple example, 8 byte or lower heap overflows and C string heap overflows caused by missing NUL aren't exploitable due to heap canaries, which also mitigate other kinds of bugs too, but they outright prevent those.
There's detailed documentation on hardened_malloc at https://github.com/GrapheneOS/hardened_malloc#security-properties. We could provide a comparison to other allocators since an accurate one does not exist elsewhere. isoalloc unfortunately has an inaccurate and misleading table. We could provide our own comparison table based around the security properties we consider important. There's not much use in a table simply saying which allocators use guard pages without comparing what they do with them and what security properties are provided. hardened_malloc has advanced features built on high entropy random bases without large protected regions, guaranteed guard slabs, virtual memory quarantines, 50% protected memory in the used portions of the isolated size class regions, etc. rather than just throwing in some guard pages.