However, I own an iPhone 4 and, to be honest, I want the other experience too.
That's a different angle altogether.
The Acer Iconia was just released for AT&T
. That was a contender when my wife and I were shopping for a tablet for her. There wasn't a version with a cell modem at the time, so it lost to the iPad. There should be some floating around that aren't tied to AT&T, since it is Acer.
The Samsung Galaxy Tab 10.1 is a nice, but more iPad like then others. Samsung does make some really nice hardware, but I'm not wowed by their software skills. I think these are locked down to Verizon's CDMA/LTE network, so probably not a good fit for someone outside of the US.
Asus is Asus. They're solid, and they have a good reputation, but no cell modems so far.
With Android, the big thing is what version is being installed on the tablet. I would wait for Android 4.0 to come out, and I definitely wouldn't buy a tablet with 2.2 on it. 4.0 will combine 3 and 2 to make a unified platform for developers which should result in better apps (or so they say), and 2.2 has security bugs in it. Plus, the 3.0 tablets will get cheap when 4.0 is released, which is an other option if you just want something to play with.
Alternately, you could get one that is supported by one of the alternative firmwares. CyanogenMod lists the Nook and Viewsonic tablet on it's list of supported devices.