Virt-a-Mate + vamX on itch:
Easy
Includes Virt-a-Mate
Free Updates Forever
Less Frequent Updates
vamX on Patreon
Requires a separate purchase and configuration of Virt-a-Mate
Frequent Monthly Updates While You are a Subscriber
More Info:
Virt-a-Mate + vamX includes Virt-a-Mate, the base game required to run vamX. If you purchase vamX on Patreon, you don't get Virt-a-Mate and it must be purchased and installed separately. Installation is significantly harder / more time consuming, as here you get a single combined installer that just puts everything together.
If you purchase vamX from Patreon, you get a newer version of vamX. That version is updated every month on Patreon as long as you keep subscribing on Patreon.
If you purchase on itch.io you get free updates for life (instead of paying monthly) but the game is only updated infrequently, typically every 4-6 months with a major combined update. These updates are checked more carefully, to make sure the major updates don't contain any issues. When the itch.io (this version) is updated, it includes ALL improvements you would get if you were on the VIP Early Access tier on Patreon, so you do end up with everything.