Looking for Wordpress hosting for our Marketing Company

I work at a marketing company and we do Wordpress sites for all of our clients. Currently we are splitting the cost of a dedicated server at HostGator with a friend that my boss knows.

The server costs us about $80 per month. We have had some issues with the speed and would like to look at other alternatives. Right now I manage all of our Wordpress sites through the InfiniteWP tool and have it hosted on a sub-domain of the server. We have the ability to do scheduled back-ups, etc. We currently do not provide updates for our client's plugins or wordpress versions. Nor do we do any type of security scanning for malware or hackers.

We manage about 30+ Wordpress websites and I would like to find a great host that would provide the following features for us.

- extremely fast speed (does not need caching at all)
- security scanning for malware and attackers
- automated updating for Wordpress core files and/or plugins
- a testing/staging environment with the ability to one-click publish to production. This is a huge on my wishlist because right now I have to manually do everything with the "Duplicator" plugin and i want to cut down my launch time.

Some of the websites I have checked out

WPEngine - http://www.wpengine.com

I have had a phone conversation with one of their support staff members and he was fantastic. The issue that I have to use them is that our budget doesn't really fit into their pricing structure at all. We already have 30+ sites to move over and their $99 a month plan only support 10 Wordpress installs, that won't cut it. Everything else on their feature list I love. They have the one-click staging environment which would be PERFECT for what I need.

Page.ly - http://www.page.ly

They seem to be very good and have some great benefits but again, their price plan is not exactly clear of how many domains we could host with them, let alone how many installations of Wordpress. They also do not have a staging platform for testing sites.

Siteground - http://www.siteground.com/web-hosting.htm

Their prices seem a little too cheap for me. They looks like they are going the HostGator route, offering extremely cheap web hosting for Wordpress. It seems to me that it would be on a shared platform at $15/month.

I am open to any feedback and would like to find the best solution possible for our budget. We might be able to go up to around $100-$120 per month but that would be the max.

Thank you all in advance!