Are you complaining about how the model looks with it's included Plasmagun?
I'm not familiar with the kit, but there's always the 5x Plasmaguns from
GW.
https://www.games-workshop.com/en-US/searchResults?qty=com.gamesworkshop.endeca.EndecaUserContext@c0fed0f&sorting=&view=&Ntt=plasma
If you're complaining about how they play in game, then a pair of meltaguns has been doing good work for me. I take a 5-man Scion squad with 2x
PG and PlaP, and a 5-man Scion squad with 2x
MG and PlaP. They work great together.
In fact, I'm not really digging Chimeras right now. I'd rather take Scions and drop them behind enemy lines, so to speak, and steal objectives that way.