My broad advice:
Keegan:
Shredder
Venom Explosive Resupply
Venom Boost
Resupply Duration
And my last card is usually Grenade Pouch, but this is Hive dependent. If I know there won’t be many grenades etc, then I’d choose something else. Recharge Bounty is a good one. Healing Module is also good if you use the ammo resupply in a combat situation.
Lahni:
Venom Blade
Thrill of the Hunt
Venom Resistance
Shock Chain
And the last card varies but I tend to choose Short-Range Resistance; or Brawler. The difference in melee attack damage with and without Brawler is relatively small and you’ll be relying on Lahni’s bleed damage much more - the time it takes for most Drone enemies to bleed out is around half a second. I tend to choose Short-Range Resistance for the extra defence, but on certain Hives where the enemy needs to die ASAP and cannot wait for them to bleed out (even though the time is relatively small), then I go for Brawler. For example The Warren has lots of Juvies at the same time, and even half a second can make a difference so most people just want them to die ASAP (especially as they have extra melee damage resistance themselves).
Mac:
Bloody Shot
Venom Resistance
Adrenaline Junkie
And the last two cards vary, but Boltok Bandolier is good for ammo, but some hives have lots of ammo available anyway so it may be less important. Crazy Tough seems popular, but I personally prefer damage resistance stats over maximum health. In Your Face is great for distracting enemies and allows team mates to run up close to enemies if necessary - works well with Lahni.
EDIT:
Also as an FYI, while the original Hivebuster characters are good and versatile, some Hives will be much easier with other characters too. Cole, Kait and Fahz are considered extremely strong characters; while Clayton and Paduk also have alot of use too. Look at it on a hive-by-hive basis!