I've been building websites for the last 15 years and as a result I have used a number of hosting companies. SiteGround is the only I use now and the only one I recommend to other people.
SiteGround includes loads of facilities and services, even in their most basic hosting package. Services that other companies make you for. For example they include a free SSL certificate, which is vital if you plan to sell anything online.
But what really makes them so good?
Unless your site loads quickly, visitors will leave it and go to your competitor. Web server response time is critical and being able to handle multiple simultaneous requests all go towards making your site more successful, and gives your visitors a better user experience. All shared hosting packages are stored on Solid State Drives which provides for a 1000x increase in input/output operations as compared to regular drives.
When compared to 12 of the other most popular web hosting companies (in no particular order: Bluehost, HostGator, iPage, Fatcow, Justhost, AsmallOrange, InMotion, WebhstingHub, Arvixe, GoDaddy, GreenGeeks and A2Hosting), SiteGround came out second.
There have been a number of highly publicised virus attacks over the last year or so. SiteGround takes all security issues seriously and was the first hosting company to introduce site isolation. Some hosting companies put your site at risk because their servers do not isolate each hosted site. What that means is that a hacker can pass from one site to another unopposed. SiteGround's site isolation effectively places a firewall around each site thus making it impossible for a hacker to attack multiple sites.
As a professional or novice site builder there will come a time when you run into a problem and need help. I did a couple of times getting this site up and running. SiteGround's customer support is second to none. There is 24-hour a day live chat or phone support, as well as an email ticket system. The staff are efficient, polite and get you back on track amazingly quickly. This means that you can get back to work and give your site visitors the service they expect of you.
To be honest the only downside I can think of, and it doesn't matter if you choose the right hosting plan for your site, is that they have a strict usage quota. The idea behind this is that the bigger and more popular your site is the more server resources it will use. The more resources you use the more you should pay, but that's understandable. You can check the status of your site at any time to see how you are doing.
Finally, SiteGround provide a free website migration service so if you host your site with someone else, you can move it to them for nothing. They claim that your site with be moved within 48 hours and you won't suffer any downtime. Other hosting companies certainly don't do that for free.