Best ETB effects

[Moneekahh]

I'm working on a casual deck and I'm looking for the absolute best ETB effects on creatures with CMC 4 or less. Any color is fine, but white is preferred. Any ideas?

[All-Mana Mania]

Mmmm, I do love me some weenies. I personally like goldnight commander for mono white human weenies. Ooh and then kessig malcontents for either Boros humans or naya humans.

[Bookmeister]

I don't know if it fits your criteria but I live {Champion of the Parish}.

[Kagain123]

Any particular format? Or just straight casual?

[Moneekahh]

Casual modern deck based around  {Emeria, the Sky Ruin}. I'm looking for creatures I'd want to ETB repeatedly.

[MuggyWuggy]

 {Azorius Arrester}
Detain is a pain in the ass

Throw in  {Whitemane Lion} to troll any attackers

[lotrwk]

A good card for ETB decks is a {Roaring Primadox}. Bounce your own creatures, play them, their effect triggers. Bounce them, play them, effect.

[All-Mana Mania]

Casual modern deck based around  {Emeria, the Sky Ruin}. I'm looking for creatures I'd want to ETB repeatedly.

Hmm. Lemme check some cards up and I'll post interesting cards

[Agarrita80]

 {Silverblade Paladin} and  {Fiend Hunter}

[Agarrita80]

 {Ravenous Rats}!!

[Cipher89]

{Acidic slime}

[Agrus Kos, Enforcer of Truth]

{Silverblade Paladin} and {Spark Trooper}. I did this to a guy twice in a row one game.

[Birdbrain]

That one drop farie that bounces a creature when she enters and is a 2/1?

[Darius]

 {Stonehorn Dignitary} could get annoying

[Birdbrain]

{farie imposter} that's what I'm thinking of

Edit: no, {deputy of acquittals} would be better. You could block with a creature, than return it to your hand before something happens