I got Hot Rod and Doublecross yesterday. They're both pretty great, but this is the internet and if the internet has taught us anything it's that two things cannot be equally good. So let's break this down.
Hot Rod's alt mode is a nice update of his original design. It has a few issues with panel gapping and not fitting together as securely as it could though.
Doublecross is a two-headed bipedal dragon
Alt mode weapon integration
Doublecross's two rifles combine and store on his back as armaments, doubling as a sort of cockpit for a Titanmaster if he lies on his front, like some kind of two-headed dragon sledge.
Hot Rod's guns combine and can sit in his engine block like that. HmmWinner: Doublecross
Alt mode Titan Master integration
Hot Rod's canopy opens and allows a Titan Master to sit securely inside. Simple, elegant.
Doublecross' chest opens to reveal a throne that a Titan Master can sit on.Winner: Doublecross
Hot Rod's Titan Master is a boring grey guy.
Doublecross's Titan Master is a robotic bipedal lion with an eyepatch, based on the Battle Beast Pirate Lion, homaging an episode of the Japanese-exclusive Headmasters cartoon.
(They're both very hard to photograph on a phone).
Hot Rod has a good robot mode. Bit loose on the hips (easily fixable) but nicely articulated.
Doublecross has a really solid robot mode where his dragon heads become his hands!Winner: Doublecross
Hot Rod has two rifles, which can combine. He can hold them in his hands.
Doublecross has two rifles which tab into his shoulders, because he can't really hold them given HIS HANDS ARE DRAGON HEADS!
Overall winner: Doublecross
(If I'm being totally honest, I could live with a bit more articulation on Doublecross' hands and arms, as it can be a bit hard to pose them well for maximum mirth about them being dragon heads.)