The MG42 is the perfect model for how an MG should function vs blobs, the MG34 and Maxim should be buffed to its level
HMG34 is fine. Basically incapable of suppressing with the first burst ever, but it's cheap so just get at least two. If it needs anything more, maybe a bit of a long-range DPS increase (not to the 42's level, of course) so it can get vet a bit faster.
Maxim should a bit of an AoE suppression so it can actually handle blobs with spotters instead of having to micro each unit suppressed, probably at the cost of increasing the set-up time a bit because none of us regard the Maxim as slow/suppressing one target poorly, and that would be a reasonable trade-off to make it better at actually locking down areas - make it take a bit more foresight and positioning to safely get down like the HMG42/34, but not quite as much because it won't shut down such a large area as hard (Ok, those two can only actually shut down the entire area with vet to actually traverse any good, but...you get me).