Awesome: Star Trek: The Next Generation/Doctor Who: Assimilation²
Issue 3 gives us a good one for the fandoms. Captain Kirk and the 4th Doctor, working side by side, two figures who are very representative of their respective fandoms. Awesome with a cherry on top.
Specifically on the Star Trek side of things, Kirk manages to fight off multiple Cybermen (to an extent, at least) with his bare hands. He even uses all of his signature moves, including his flying kick and the infamous two-fisted hammer punch.
The Doctor, on the other hand, keeps his cool under pressure throughout the entire brawl, calmly asking Kirk for his communicator so that he can use its cover to generate a cloud of gold dust, immobilising the Cybermen long enough for the rest of the Enterprise crew to finish them off with their phasers.
In the final issue, when a Borg drone attempts to assimilate the TARDIS, the TARDIS Matrix takes refuge in Lt. Cmdr. Data. When the situation is resolved, all Data can say about the experience, "Fascinating."