If you are considering SiteGround web hosting provider, I must say you should go with them. But if you want me to compare GreenGeeks and Yahoo's web hosting services, I would recommend you to go with GreenGeeks.
GreenGeeks has been the industry's leader in eco-friendly web hosting services Since 2008. GreenGeeks has cPanel where as Yahoo has in-house developed panel.
GreenGeeks offers shared hosting plan @ $2.95/month with
Free Domain Name
Free SSL Certificate
Unlimited Disk Space
Unlimited Domains Hosted
FREE Website Transfer
and Many More
Depends on what stuff are you going to host , is it a wordpress website or a simple HTML website , or an online ecommerce or what ? ... Just dont run behind the cheap provider. First evaluate your requirements and then accordingly choose the hosting provider.
For me, some reliable features should be there in your web host mainly 100% uptime, should have very good customer support, which secures your website and provide these services in a reasonable price. It also depends upon your requirements what type of hosting your website actually wants and what amount of traffic your website would encounter in a period of a month or two. If your requirements are high then you should go with GreenGeeks.