This is a terrain priority list for both games as of March 2017. This is for the serious map markers who may need a reference, beyond practical experience, that show which terrains will dominate and which will be dominated by other terrains higher up the priority list.
So the first ones on the list are the lowest priority and the end of the list is the highest. There are many other terrains not listed ( trees , roads, railway for example because they are handled differently than "earth" terrains.
winSPWW2 and winSPMBT terrain priority as of March 2017
P10_TER95 - Red Earth
P11_TER81 - Earth
P12_TER63 - Red Sand
P13_TER83 - "Beach" Sand
P14_TER65 - Gray Sand
P17_TER20 - Sand
P18_TER55 - Volcanic Sand
P20_TER70PB - Dry Grass
P22_TER00 - Green Grass
P23_TER87 - Grass_2
P24_TER89 - Grass_3
P26_TER44 - Mud
P30_TER93 - Forest Groundcover
P33_TER36PB- very light snow
P42_TER70PB Winter scrub
P44_TER07 - High Grass
P46_TER14 - Sand Dune Patches
P48_TER85 - Cobblestones-Brick red
P49_TER86 - Cobblestones-Stone grey
P50_TER28 - Pavement Hex
P53_TER10 - Snow
P55_TER37 - Winter Snow Drifts
P56_TER35 - Winter light snow
P59_TER72 - Tall Dry Grass
P62_TER02 - Rough
P64_TER79 - Red Sand Rough
P65_TER18 - Sand Rough
P67_TER67 - Gray Rough
P70_TER12 - Rough Snow
P73_TER16 - Winter Swamp
P76_TER62 - Swamp 2 ( Jungle )
P79_TER05 - Swamp
P82_TER48 - Impassible Ground level
P85_TER17 - Winter Crops
P88_TER42 - Rice Paddy
P92_TER58 - Tilled Fields
P95_TER04PB - Green Crops
P98_TER33 - Yellow Grainfield
P101_TER60 - Mid Winter Fields
P102_TER04PB - Harvested Field
P103_TER74 - Crop Stubble Fields ( winter )
P109_TER78 - Winter Stream Joins
P119_TER76 - Ice
P120_TER22 - Water
P121_TER97 - Deep Water