
The Galactic Patrol has been given the ultimate weapon in its war against the evil pirate Boskone: The Lens. But even though the Patrol's Lensmen are the most feared peacekeepers in the galaxy, they aren't quite sure how to use their unique gift. Things are about to change, however. Kimball Kinnison has just graduated from the academy, and now that's he's earned his Lens, he's determined to figure out how it works. Kinnison begins his journey of discovery by taking command of the Brittania, an experimental ship that's as likely to kill him as it is the Boskone raiders it was built to fight. That leads him on a series of whirlwind adventures that include a visit to the planet Arisia--where the mysterious creators of the Lens make their home--and end up in a confrontation with Helmuth, who may well be Boskone himself. Although this is the third book in the Lensman series, it's the novel where, as SF critic John Clute puts it, "the story has started, and it does not stop." This is a rip-roaring tale of heroes, aliens, space battles, and bold deeds, the stuff that Golden Age science fiction was built from. --Craig E. Engler
Some of the closest would likely be:
Charles Stross' various SF, especially the space opera-adjacent stuff. (He has an large range. Merchant Princes and Laundry series are good, but not at all along the lines of Banks.)
Gregory Benford's Galactic Center Saga.
Vernor Vinge's three Zones of Though books.
David Brin's Uplift series.
Perhaps Hannu Rajaniemi's Jean le Flambeur series.
Max Gladstone's Emperess of Forever shares a similar setting, but is much lighter.
The writing of Gene Wolfe and Tamayn Muir has, I think, much in common with Banks in terms of depth and character, but even though SF they have a very different feel and focus to their works.
And, of course, if you want the original space opera, it might be worth tracking down E.E. "Doc" Smith's Lensmen books. Galactic Patrol and Grey Lensman are the heart of it and ought to be read first. Second Stage Lensman and Children of the Lens are worthy sequels that complete the story. They're pretty breezy reads and very different from Banks in everything but the setting of a galaxy filled with different species, and likely seem somewhat hackneyed now, but they're also the source of most space opera archetypes. (If you think of a space opera trope, it probably came from Lensman. Star Wars is largely a Lensman/Flash Gordon mashup.)
(My fondness of Smith's works would later cause me to confuse the names of Ford's Mercury Tracer and Honda's CR-X.)
And while not identical, Smith's Lensmen and Lucas' Jedi Knights have a great deal in common.
