Depends on many variables (where you are and how many hours you going to work.., part time of full time..) Generally Verizon has the best coverage in most states, 8gb of data or more should be good enough.
I have multiple lines grandfathered on cricket under 'old' multi line discount on an unlimited plan. That being said...
My data use at beginning was high, prior to U/L, from use of Waze, GMaps, etc for nav purposes. Found a hack to force Waze to cache a larger area (hack patched now) and jumped at GMaps offline maps option. Download various maps before you need them. I have nearby states major cities cached now. When on wifi, is auto updated.
I switched phones from S4 to V20. Data use was quite higher than I expected. Several hundred megabytes each night for each U & L app. It was map component. Found that GMaps is used internal, remembered offline maps option, and started downloading over wifi. Next weekend, total data was a 150 to 200 megs fir both apps combined.
Why go through the process of using offline maps? I am convinced the apps go sideways when throughput slows, like congested area or in the sticks. Offline maps removes majority of information that is needed to be received by phone, opening up bandwidth for other app activities. It definitely works for me, and doesn't cost anything extra.