Speed is probably the main consideration when choosing a template for an e-commerce site as website visitors will browse away if they wait too long. Tools such as https://gtmetrix.com and https://tools.pingdom.com can provide a rough idea of the performance of a template. Run the speed test as close to the location of the demo website by choosing an appropriate server location when running the test. (Create a free account on GTMetrix to be able to choose a server location).
SEO features (page titles, page headings, meta descriptions) are built into the Joomla core rather than the template although some templates implement these poorly and should be avoided (e.g. early Artisteer templates implemented the page heading as a H2 heading rather than a H1 heading. There are also many third party extensions that can help with SEO.
Choose a template from a template developer that offers ongoing support and updates so you are not left stranded when there is a major Joomla update etc.
Some templates are specifically designed to integrate with one or more e-commerce extensions and this may be useful if you are using one of the more popular e-commerce solutions.
Recommending specific templates may turn this into a community poll so all I'll suggest is to choose a fast template from an established template developer. It doesn't have to be a template specifically designed for e-commerce but any e-commerce extension specific styling is probably a bonus.