Best deal and best service I've ever tried has been SiteGround, who've hosted a few websites for me for the past few years. On the rare occasion that my service has felt slower than normal (I've never had the site go down completely at all), within a day or two I've gotten an email from them saying my site was not performing optimally and they were moving me to a newer, better, fast server, usually also providing more storage (now moot, I have unlimited storage) and other new features. Never once have they raised the prices on me either, despite these upgrades.
Link that lists me as a referrer:
SiteGround.com
Direct link:
SiteGround.com
EDIT: Forgot to mention, but if you PM me, I've got some $20 off coupons I can email. Anyone interested is welcome to one, as long as I have them available.
If you're set between the two you brought up, I've heard quite a few good things about ASO, but little about Thinkhost.
jW
