Seisenshi Dunbine

Of all Tomino's non-Gundam works, Aura Battler Dunbine is probably the closest thing to basically being another Gundam, a <i>medieval Gundam</i> perhaps. Above all a lot of the characters and the general tone of the show feels closer to Zeta rather than the original Gundam series and others, so if you enjoyed the grimdark storytelling through Zeta and are a fan of Tomino's style, then definitely check out Dunbine. Oh and yeah, both are "Kill Em' All" Tomino for the record. 

Both are fantasy mecha series in which a person from Earth gets isekai'd to a medieval world and use their knowledge to create giant robots and new weapons. The main difference in this aspect is in how that person is portrayed - in Dunbine he's a villain and shown in a negative light for proliferating arms and warfare, while in K&M he's the main character and shown in a positive light for his genius and rapidly advancing technology. There are other notable differences, while both series have large ensemble casts, K&M is more focused on the development of the machines while Dunbine focuses more on the actual war at hand. read more 

the post-apocalyptic world of nausicaa and the fantasy world of byston well in dunbine have a very similar feel to them in my opinion, and the efficiency with which these anime build their worlds is impressive in both cases. additionally, the mechanical and creature designs of the two would likely appeal to similar audiences. in fact, because the nausicaa manga had already begun its serialization by the time dunbine aired, it's not unreasonable to suggest that dunbine director yoshiyuki tomino and nausicaa creator hayao miyazaki may have been vaguely inspired by each other's work at the time. 

Both have similar plots where the main character starts off as a member of a one faction, but quickly defects to a freedom fighter/rebel group-type faction where he stays for the rest of the show. Both shows are also directed by Yoshiyuki Tomino, and share many of the quirks of his style. Dunbine is a much easier watch, as it is paced more evenly, while G-Reco is paced very quickly and requires the viewer's full attention. 

Garzey’s Wing is basically Dunbine without mechs. Their baseline plots are quite similar, with the biggest difference being that Dunbine is actually good. 

Classic Sunrise's dab into medieval mecha. Although there's obviously the futuristic mecha aspects, both shows also have some weird elements of sci-fi mixed in with its fantasy as well (moreso with Galient). You've got Dunbine directed by Tomino (Gundam) and Galient by Ryosuke Takahashi (Votoms), so they have their differences but if you like 80's mecha these are both definitely worth checking out.  

In both series, the main character is mysteriously beamed from present day Japan to a medieval, parallel world that is somewhat similar to our own; in Dunbine, we have Byston Well, a land somehow contained within the Earth, and in Escaflowne there is Gaia, a land orbiting the earth but somehow invisible to it. These parallel worlds are both ravaged by war because of the sinister plans of men who have also crossed between the worlds: and 'war' in both cases, is fought by humans who pilot bio-mechanical robots. Both Escaflowne and Dunbine have their pros and cons. Escaflowne is much shorter, but Dunbine is overlong. The central character of Escaflowne, Hitomi, brings significant Shoujo elements to the story, creating a more androgenously targeted show (whether that is a pro or a con to you varies. Personally, I think this detail gives Escaflowne the edge, as it becomes less of 'just another Robot fight'). Obviously, Escaflowne is a more modern series and Dunbine has pretty primitive animation... but if you enjoy one, it is well worth hunting down the other! read more 

Both are isekai-themed fantasy animes with a common theme of items, weaponry, and concepts from Earth affecting a fantasy world. Zero no Tsukaima is more comedy focused, while Dunbine is more focused on military drama. The main characters Saito and Sho share some similar character traits initially, however develop differently as their respective franchises continue on.