I disagree. Having play tested the Mk. 1 model of this thing against the MM bot, have found it lacking. While there are loser configs of the Kingfisher, I'd probably want the Kingfisher in most instances. The Prime, A, C, and F look like they would be superior choices to the Onager Mk. 1. Exceptions such as heavily built up areas and/or badlands might alter the balance, but, as is, it makes me think of a confused Highlander.
The Mk. 1 seems to use the least efficient propulsion systems in tandem. It then goes on to blow additional tonnage on a Hag 30. Did the Falcons pick up the "taint" of more speed than brains from the Ice Ferrets? And, apparently the Falcons were having problems with their scientist class... if the "micro" weapons were garbage on the protomechs, why would anyone think they get better on real 'mechs? Sounds like some scientists need to be taught a lesson in dial-a-yield lasers, starting from their peripheral appendages and slowly working in toward the gooey center.
Quirky, eclectic, eccentric, "flavorful," etc. don't win wars. Functional wins wars, lots of functional hard-hitting units win wars. With some of the designs coming out of clan-land, it's amazing they actually get anything accomplished militarily.
I find them very similar:
Long Range: Both mechs get 30 points of possible damage at long range HAG30 for Onager, 2 Large Pulse Lasers and LRM10 for Kingfisher
The Kingfisher has a more concentrated punch from the pulse lasers, but the HAG 30 about evens out by virtue of being more likely to get a KO or TAC from multiple hits, the increased accuracy of the pulse lasers is countered by the HAGs superior range to get similar numbers so overall by staying one bracket away. The HAG suffers performance penalties but at long range it can fire outside of a range the LPLs can reply. In my book I find their long range performance is somewhat similar.
Medium Range: Things start getting a little bit more interesting here both mechs have a very similar short range armament: Including their long range guns, they begin to bring 2 medium pulse lasers each, and srm6s. The Kingfisher has a bit more range with the more efficient streak but the Onager somewhat makes up for it with paired srm6s with 2 tons of ammo. Those two tons allow for flexibility by bringing infernos or tandem charges.
Short Range: Both mechs get to add a tiny bit more firepower, this this regard the Onager comes slightly on top with increased maneuverability to get into rear arcs or avoid the KF getting in its rear arc and a few more small lasers.
This analysis is of course comparing it to the PRIME variant. Are there better mechs? Yes. Is the Onager a bad mech? Probably not. Optimized far from it, but it makes it quirky while still remaining effective. It is no Jade Hawk but then again few mechs are. And as a Jade Falcon I do love my Jump Jets so the 5 jumping is not strike for me, even when not necessarily efficient! And I do love bringing me a ton of infernos in my Onagers and Flamberges! :D