What is a good verb to describe the pleasant sound of rain?

Maybe 'sprinkle' or 'patter' or 'pelt'?

Cadence: the modulated and rhythmic recurrence of a sound especially in nature

There are a lot of good idiomatic phrases in English for rain:

The rain pitter-pattered on the roof top.

"Pitter-patter" means light sounds or beats, and often is used to describe the sound of small animals (like cats) as they gently move about. It has a fairly positive and easy-going connotation, and using "pitter-patter" to describe rain invokes a sense of melody and calm.

The rain sprinkled on the roof top.

"Sprinkle" means scattering or dispersing. It generally is applied to small objects, like dust or sugar coatings. When describing rain, it generally implies that the rain drops are small and gentle. It can imply a feeling of spreading in a haphazard or unguided way. For this reason, it has a fairly neutral connotation, generally meaning light rain.

The rain showered the roof top.

"Shower" means a lot of water, should evoke the feeling of being in a shower. It creates a sense of a large quantity of water, coming down in large drops. It's not necessarily aggressive or negative, but implies lots and lots of water. A "shower" of water on the roof wouldn't be resolvable in individual drop sounds, but would instead be a steady drone of noise.

The rain pelted the roof top.

"Pelt" means to attack with objects. Here, it should evoke a sense of anger or aggression, as if the water were throwing itself in attack at the roof. "Pelting rain" would be large, fast drops, coming down hard.

The rain battered the roof top.

"Batter" means to beat or attack. Generally, it always evokes a sense of aggression and violence. When used with rain, it often implies a type of windy rain, as the wind and the rain "work together" to attack the building. In the minds eye, you might see shutters banging about and hear the whistling of the wind when you imagine "battering rain".

There are a lot more phrases, but these should get you going. If you are looking for a more specific connotation, I'll see what I can come up with.

If you perceive a musical quality in it, you might choose tintinnabulation (although it is often reserved for bell-like sounds)

A ringing or tinkling sound. [Oxford Dictionaries Online]

As I type, I am listening to the plashing of the first significant downpour of rain to fall in central (aka "northern") California in seven months. Here is Merriam-Webster's Eleventh Collegiate Dictionary's definition of plash, which I was surprised to learn has been in use since at least 1513 as a noun and 1542 as a verb:

plash vi (1542) : to cause a splashing or spattering effect vt : to break the surface (of water) : SPLASH

The intransitive form of the verb is the relevant one here.

You are trying to convey not only what the rain did, but how it made you feel. Metaphor is an option: strummed, thrummed, tinkled, drummed (musical metaphors) whispered, sighed, groaned, grumbled, danced, tap danced (personification)

Other possibilities: plinked, beat, droned, roared, rushed, whooshed, crashed, careened, tumbled, tapped, gurgled, thundered

Perhaps not strictly focused on the sound:

More figurative (and may require additional words): enveloped, enfolded, embraced

And the more literal choices: streamed, poured, deluged, doused, submerged

"susurration" is probably what I would use.

Because nobody has said it yet, I like the word trickle.

It gives a sense of light, calming motion and can sound both poetic and whimsical.

Rain.

As in: I enjoyed the sound of rain on my window and on my roof.

I am not trying to go all Hemingway or William Zinzer on you, but we often rob everyday nouns of their strength by using florid adjectives or baroque words. The reader or listener can be trusted to connect with the sentence that you wrote with his or her own pleasant experiences of the sound of rain.

This question reminded me of an old favorite ABBA song: "The day before you came",

And turning out the light
I must have yawned and cuddled up for yet another night.
And rattling on the roof I must have heard the sound of rain
The day before you came

Songwriters: ANDERSSON, BENNY GORAN BROR / ULVAEUS, BJOERN K. The Day Before You Came lyrics © Universal Music Publishing Group, EMI Music Publishing

One of my favourites is:

Outside the rain is tapping on the leaves, to me it sounds like they're applauding us the quiet love we've made.

--Ray Lamontagne, Empty

Such a beautiful imposition of the humanity found sometimes around us in the natural. Certainly we can see this beauty clearly if we are only in the right mood.

Susurration is a soothing word, a whispering sound.

There's always this song asking us to "Listen to the rhythm of the falling rain".

I don't remember where I've seen this, but, 'pleuvisaud' has been used to describe the pleasant sound of rain. In particular, the comforting sound of rain on a roof while one is inside.

I enjoyed the sound of rain on my window and my roof.

I enjoyed the sound of the rain beating against the window and on the roof.