DA/DB/DC/DBR - the Atlas (early ones made by Kato) SD7/9s or the newer SD24/26/35s (generally DCC friendly) are a good match and run well. You can chop off the brake shoes that surround the center axle to represent our locos. Technically the idler wheels should be a smaller diameter, but who's going to know... These all run very well. The Lifeline SD7s of about 10 years ago are ok, but they are light and really need their power pickups hardwired between the bogies and the chassis.
DE - I reckon one of these would be a good start: http://www.euro-trains.com/products/Roco/23393.aspx
DF (EE) - Kato makes several Japanese 2-c0-c0-2 electrics that are within spitting. The end bogies are the right design, but a little small. The driven bogies on the Japanese loco have an offset middle axle, but it's not far off. I bought one of these chassis about 15 years ago but have yet to start construction. The one I got came with nicely molded clip-on cowcatchers as well.
DF (GM) - Kato sd40-2s are pretty good - these are all DCC friendly. The design of the chassis and bogies were changed on these about 3 years ago from the earlier models. As discussed in a much older post, you can use the larger SD90 wheelsets in these bogies for a slightly better look. The SD fuel tank is fairly close to the DF's in profile (the SD's slopes more in at the bottom) if you cut the back off to make room for a plasticard battery box.
DG - PA1's made by Con-cor/Lifelike/Kato. I have no experience with the Lifelike models. I think the early Con-cor ones from about 25 years ago were made by Kato. They run well. Kato redesigned these a couple of years ago to make them more DCC friendly, but the metal chassis is now a bit longer than we'd like. The pic below shows the required surgery to fit my old recab.
DH (GE) - Haven't measured one, but I think the new Atlas MP15 http://www.blwnscale.com/Atlas%20MP15DC.htm might work well for a DH as it's a bit shorter than the other GP models.
DI - Nothing springs to mind. My hokey example was made from a GP30 chassis with SD40-2 bogies (one reversed). Yikes
DJ - There are a bunch of tri-bogie Japanese electric loco prototypes with small gaps between the bogies (we don't want the long locos with spaced out bogies). We also want twin coil springs on each bogie side, but these are hard to find. I think I used this prototype for mine: http://www.1999.co.jp/eng/image/10031056a/20/1 If I do another DJ, I might get one of these EF64-37s. http://www.newhallstation.com/store/product_info.php/cPath/26_30/products_id/420 The centre bogie has only one spring, but on the plus side there are no bogie-mounted sandboxes to have to hack off. The newer ones may be more DCC friendly than the old ones. The other challenge is that the metal chassis halves are full width so are a bit fat for a DJ hood. You can try filing/milling them down.
DX family- The recent Atlas Dash 8s are very nice and are DCC friendly. They are nice and narrow. Bachman's older models from the early 1990s aren't in the same league, but they're not awful and can be had cheaply off ebay if you can find someone who will ship internationally. I got three from a guy in the UK for about $50USD. Their newer releases from a year or three ago are supposed to be much better, but they're almost as pricey as the Atlas ones. To complete the DX illusion, you can reposition the brake cylinders, add the shock absorbers on all but the center axles, and add the inboard 'tail' to the main bogie casting. The DX has a pretty short fuel tank as well, but it's a similar profile to the Dash 8's, so you can cut down the one that comes with the chassis and fatten it up a bit.
So that's my brain-dump - who has other experiences and suggestions?