If you look for userdata typically a subset of the following features are used for personalisation:
CUSTOMER BASICS
Customer ID
Customer language
Customer age birthdate
Customer gender
Social Channels
PRESALES
Number of free trial products
Product type trial evaluation etc
FINANCIALS
Payment type
Net value || Customer Lifetime Contribution (CLTC) || Lifetime Value (LTV)
Credit card expiry date
Charging date payment
Discount received
SHOPPING DATA
Product families related owned
Total number of product owned in history
Time diff between purchases
Products owned
Purchase Date
Subscription type
Payment gateway where transaction was performed
Number of total purchases per communication channel
Active contract runtime
Time to renew expiration
Acquisition source
Subscription status switch
CUSTOMER SUPPORT
Last touch timestamp customer reaches us actively
Last touch timestamp we reached customer
Last touch Customer support
Customer complaint
Subscribed Unsubscribed status Newsletter
CUSTOMER BEHAVIOUR
Last touch element
Device OS
Number of visits of the website
Period of inactivity
Number of visits t website in recent X months…
Number of carts created abandoned / completed
Number of clicks
Average time spent on website
Unsubscribe date
Date last contact per channel
Number of contacts in last week 1 month 2 months…
Purchase behaviour: campaigns, sales event etc