Well if you just want locals you really could get by with a Silver Sensor indoors, but if you want a selection, go for the biggest antenna you can afford. I'm in Flushing and at this point I get about 15 ota HD/DT stations. I'm using a Televes antenna and a Channel Master 77xx series preamp. Overload is not a problem, I can see WEYI' s tower at night from an upstairs bedroom. While the Televes is a little hard to get and expensive now, I'd opt for a good old 8 bay bowtie from CM along with the 77xx preamp, seems to be the hands down overall favorite in these forums.
In case you're wondering here are the channels I get: 14-1, 15-1, 21-1, 22-2, 30-1, 36-1, 38-5, 41-1, 44-1*, 44-1*, 45-1, 55-2, 57-3, 58-2, 59-2 , 43-1* (I'll leave out the call letteres and their remapped locations, too much typing..)
* 44-1 WWJ-DT & 44-1 WZPX Lansing/ GR depending on antenna position, 43-1 Weather dependent due to WZPX analog.
As for D, I've had both D and E* at the same time and I'd say they were about equivalent in quality. On a 55" set you might notice some artifacts, but less with D due to their methods of compression, instead of blocks it just appears softer. If you tweak your set a bit you should be fine. I'm using a 38" direct view and if I get close I can notice it but I tend to watch the show and not the picture so it really doesn't bother me too much, I know others feel different. If your moving up from cable anything is an improvement. I finally got my aunt to switch and there is a world of difference on the analog package level.
Note: if you're looking at D, find a relative or some vacant land in Fenton or below to use as a service address, you can use your home address as a mailing address, this is called "Moving" do a search here and in the TiVo forums if you're unfamiliar with the term. Flint is in a Pegasus area, which means D customers here pay more for less. If you are in Fenton or south, you can get Detroit locals, in Flint there are none yet, possibly in a month or two, but you will still deal with the Pegasus service charge. If you're looking at D then be sure one of your units is a DTiVo, at $99 it's one of the best deals out there. There will be a HD TiVo soon but at $$$. As a previous customer of E*, their service if fine, their PVRs are crap.