I have a Comcast business line. While I've never tested the unlimitedness of it, it does have its own sets of pros and cons:
+ Constant, consistent price. There are no promo deals of any sort.
- More expensive by $15-20 per month.
+ Cable modem is provided (they call it the Comcast Business Gateway) at no additional charge.
- They call all of the freaking time trying to upsell you on voice service. Seriously, like 6-7 times per week. I finally blocked their number from being able to dial my phone.
+ TV is "only" $5 per month more for the basic channel lineup