I've never had issues with releases until joining on with micros. There are some paranoid dudes out there. iStock won't accept a Getty release even though they are owned by Getty. Dreamstime won't accept a iStock release because:

The attached MR/PR is signed specifically for another agency, or it is not generic in terms of the laws that govern the agreement. The model release represents a written agreement between the model and the photographer, therefore it must be governed by the laws of the country/state where the parties reside, or by international laws. Please use our own model release document or a generic one in English.

It's a bunch of whooey. There is no way I'm getting models to sign a bunch of different release.

Does anyone know which one is generally accepted by all the micros.

I used the Istock release, scanned it as jpg and in Photoshop cut and removed the Logo and the location text "saved it as" with a new name, then it was accepted at DT.

Less messing about than asking for a couple of releases

David