Which is the best antispoof code between these?

[aleunix]

Blocking Spoofed Packets
Given this initial code:

# Macros
# The external interface (connected to internet)
ext_if="re0"
# don't filter on the loopback interface
set skip on lo0

Which is better between these follows code?
1)

antispoof quick for $ext_if

2)

antispoof quick for $ext_if inet

3)

antispoof quick for { lo $ext_if }

All these variant works, previously i used the last because exist even an example here:
The Complete Ruleset
but i have the impression that isn't useful given the skip instruction.
Using the first i can drop even ipv6 address (now i'm using ipv4 address).

[aleunix]

Now i'm using the first choice so i can avoid to change the code even if in future there is a change from ipv4 to ipv6.