I think more enemy variety instead of using the same groups over and over would make their encounters more enjoyable. And if all three mercenary groups practically behave the same then what's the point in having different groups? What difference would it make if they were all made to be a part of one group, such as CAT6 from ME3's Citadel DLC? Blood Pack is fine I guess since the krogan aren't really known for much else besides brute strength and they aren't encountered much compared to the other two. Perhaps just get rid of the vorcha and have all members be krogan. That would make a tough group to fight given how strong krogan are. Eclipse should be made up exclusively of Asari that fight with biotics and have technology to enhance them and combat droids to reinforce them. Blue Suns should be professional soldiers that utilize combat tactics from different races. Less hi-tech and no biotics but dangerous to take on due to the experience of their members and the varying combat techniques from each race. TL;DR these three groups don't really add anything other than "mercenaries trying to kill you". They all practically fight the same way. Better as in better than the trilogy or better than it's perceived currently?