Soukou Kihei Votoms: Case;Irvine

This a list of all Armored Trooper Votoms anime in release order, which is also the recommended watch order. MAL's relation system doesn't really give an overview of the franchise and its structure.
Recaps are marked and any special content is noted in case you want to skip them, and release order is clarified for the 80s OVAs.

Armored Trooper Votoms is a 1983 Mecha anime directed by Ryousuke Takahashi, noted for being one of the landmarks of the "real robot" subgenre, i.e. the treatment of mecha as simply military machinery instead of super heroes. The franchise is primarily built around this main TV show and fleshes it out with various prequels, side stories and sequels in a non-linear fashion, with a few spin-offs that make use of many of the elements of the world while not directly relating to the main story.

Sunrise's 80s OVA policy was to release a number of recap OVAs, then follow them up with new content, and then if that sold well they'd put out more recaps with more new content at the end. Votoms isn't the only show to see this policy, but it's the one where they did it the most. This is how The Last Red Shoulder, Big Battle and Red Shoulder Document came to be.

Armor Hunter Mellowlink, Case;Irvine and Votoms Finder are spin-offs that have varying degrees of connection to the main Votoms story and world, Mellowlink being the closest, and Finder being the furthest removed (in fact you may struggle to find a reason why it's called Votoms).

While the franchise has been dormant since 2011 as Ryousuke Takahashi has mostly retired from the directing anime (with a few exceptions in the last few years), there are a number of novels set in the Votoms universe that have been released in the last 20 years but have not been adapted to anime. These include Commando Vorct, Blue Knight Berserga, Philosopher on the Battlefield, and Child of God. Some of these may be adapted some day (in fact there is a doujin anime of Berserga on Youtube), but I wouldn't hold out hope.