I have personally use following on different moodle installations, plus some other recommendations:
Hostmonster: There are users having trouble using them, but I have been with them for 9 years and havent had any trouble, I had used moodle installation and at times there were 80+ concurrent users uploading assignments and never missed the beat, Only issue with me when I was with them was they only offered shared hosting that time, but a year back they now offer several packages, like Pro hosting, VPS, and Dedicated as well, so you can upgrade as when needed. Unlimited Space & bandwidth. Website HERE.
CrocWeb: I was recommended CrocWeb at a busy hosting forum, and I went for their Valentine's offer just to see if they are what they claim, & I found them to be worth recommending without any obligations, they though are resellers, but serves are fast, reliable and uptime's been very good. I will recommend them based on LiteSpeed servers, SSD discs, and you have all PHP extensions that Moodle recommend (Like opcache) and as well MariaDB, and I have found significant improvements on testing moodle site using opcache. Limited Space & Bandwidth. Website HERE.
StableHost: They have same reviews as CrocWeb, their package of Enterprise hosting will handle your even 200-300 concurrent users without hassle. Though i havent personally used them to tell about PHP extensions available. Limited Space & Unlimited bandwidth. Website HERE.
HosterPK: They have same configurations like CrocWeb (in terms of LiteSpeed servers and PHP extensions), though I am unsure about SSD Discs, they are resellers and are based on several different servers (Like Limestone Networks and many other reliable companies), their rates are cheap and they claim their Unlimited package is as good as an entry level VPS and their Portal Package (you've to order it through email) is as good as a strong VPS. I have seen heavy video websites running on their servers with very good uptime. Unlimited Space & bandwidth. Website HERE.
Hostwinds: They have LiteSpeed servers and as per their claim, their Business Hosting (started from just $5) is as good as their Level5 VPS, Unlimited Space & bandwidth with Dedicated IP Address (thats recommended). Website HERE.