Zero no Tsukaima, Toradora! Recommendations
The obvious similarity pertains mostly to the main female characters of both manga, tiny but very proud and violent. Taiga even looks almost exactly like Louise except with brown hair.
Both manga involving romance around "tsundere" girls and they treat their partner so badly at first till they develop romance feeling while the story progressing.
The story and plot are completely different but the similarity between character and the way they share their bond together are obviously the similarity.
Both are manga adaptations of light novels revolving around the romance of the main protagonist (both goodhearted guys, but not too similar) and the female protagonist, which is a short, temperamental, dangerous, pettan and purposeful girl (but with fragile hearts). Their appearance is also very much alike, with the exception of hair colour, so in a sense the artstyle is alike, both are already classic tsunderes and a prime example when talking about that type of characters. As a side note the romance and comedy is handled similarly, also.