I have a janome derby portable machine. Janome Pink Lightning Basic, Easy-to-Use, 10-Stitch Portable, Compact Sewing Machine with Free Arm only 5 pounds https://www.amazon.com/dp/B00H34GP6O/ref=cm_sw_r_cp_apa_i_nPH-AbH5TR174 if storage size and weight is what's most important to you, I'd recommend this one.

I've also used a vintage singer featherweight and a modern singer mini machine. The janome derby is better.

However, a basic full size machine will give you more value. This is a perfect first machine, and not much more than a good portable machine. Brother XM2701 Lightweight, Full-Featured Sewing Machine with 27 Stitches, 1-Step Auto-Size Buttonholer, 6 Sewing Feet, and Instructional DVD https://www.amazon.com/dp/B00JBKVN8S/ref=cm_sw_r_cp_apa_i_qUH-Ab7N1DNA4