Fluid layout that I control - so I want maybe three columns with search and perhaps directory information in the middle and I want to be able to fill the left and right columns with blocks of information from your site in the manner that I decide.
So maybe I would want regional weather at the top left and news underneath that (your services) and at the right I would like messaging facilities (SMS or instant messaging) and underneath that a block showing the latest postings in any forum threads (or other "community" related stuff) that I'm keeping an eye on.
Yahoo! have attempted to do this, but it doesn't offer you a great deal of control. However you try it, the page ends up looking messy (a reason I don't use a portal, I just built my own "homepage" using a couple of iFrames).
I want complete control - if I just want a blank white page with a search box in the middle (like google for example) and maybe a link to a couple of your services, then I should be able to have that.
I like a homepage that's clean and simple. Others will want to be bombarded with stockmarket quotes and news stories. So the more customisable it is, the wider audience you would attract.
I guess a facility to achieve the same result as if you had built your own homepage from scratch (like I did), importing the content you want from your selection offered and placing it where you want. Oh, and I don't want any adverts I'm afraid!
And it goes without saying that the quality of content that you offer is critical.
This is of course, only my personal view on it, but does that help?