If you want to attract the best software engineers, offer a work environment that constantly challenges them to learn and grow both professionally and personally. Expose engineers to a wide array of technologies, let them explore and narrow down their interests, and always allow for a change of course should they get bored with their chosen specialty.
Put your engineers in charge of high-profile projects, ensuring they have ample resources, appropriate support, and realistic deadlines. Encourage them to speak at industry events, pen thought-leadership articles, and volunteer in the community to nurture a sense of fulfillment and personal growth.