868Mhz, OOK (AM) or FSK (FM) which is more common

[Dave21w]

Does anyone know what modulation method the majority of 868Mhz devices use, I currently have some 433Mhz (AM) Door contacts but due to the number of Temp sensors I have and local 433Mhz stuff around me the open / close signal sometimes gets missed due to data collisions, for a Temp sensor its unimportant as they update every few minutes but if the door closing signal is missed then as far as Domoticz is concerned its open and thats the way it stays therefore I plan on converting my door contacts to 868Mhz however if I'm going to buy or build a Transceiver for this band I'd like to comply with the most popular format for transmission.

There's no issue with the mod as I can program the chip for either transmission mode, I'd just like to choose the right hardware for the transceiver the first time

Thanks