Here are TOP Best Marketplace Themes for Magento Ecommerce:

1. Landofcoder Bicomart Marketplace Themes for Magento 2 Ecommerce
https://landofcoder.com/ves-bicomart-magento-2-marketplace-theme.html

- Comes with 03+ Marketplace Demos Homepages & Powerful Feature for Seller
- Highly compatible with Landofcoder Magento 2 Marketplace Extension
- Optimize for SEO & Speed
- Mobile Friendly
- Unlimited Customization

2. Venustheme Ves Bestmart
https://landofcoder.com/ves-bestmart.html/

Ves Bestmart comes with elegant, eye catching design. Created with product-oriented in mind, the theme bring you white background, eye-catching slider, neat & clean layout that helps you showcase products at it's best.

3. Venustheme Ves Evolution
https://landofcoder.com/ves-evolution.html/

Ves Evolution is a powerful and flexible Magento 2 theme to help you make the greatest use of an online technology store. This theme is designed basing on the increasing demand on electronic device such as Laptop, Tablet, Mobile, Accessories, Camera, Headphone, TV & Video, Smart Swatches, Computer, Video Games, Speaker, Home Audio & Theater, Car Electronics.