It Doesn't matter that much, but I would stick with BlueHost or Hostgator. The one advantage to BlueHost is that you get one domain free. This is your Hub site and all new domains you buy will be a subdomain to the hub. The same is true for hostgator expect you don't get a free domain.
Secondly - if you are going to follow the steps as outlined in Marucs New Affiliate Marketing Toolbar, go with Bluehost as this is the hosting company that Marcus uses in all his training videos and courses.
Again you can use any hosting company, but stay with Bluehost or hostgator. The pricing for hosting domains are roughly the same with either company. Also it doesn't cost any more money to have hosting for any number of domains you Add to your Hub.
I use Hostgator, Only because I've been using them for a little over 2 years and happy with them. Plus I'm beyond the point of needing to follow Marcus training with respect to where to buy domains, where to host my domain and set things up. But I highly recommend you go with Bluehost and follow Marcus to the "Tee".