Hello
I trekked Langtang, Gosainkund and Helambu last August and, although it was wetter than I expected and wetter than usual accordint to the locals, it was still an enjoyable trek. I think the trick is to expect and prepare for some rain both mentally and with the right gear.
Of the two areas you mention, the Annapurna Circuit is probably the best option: Most of the trek is in the Himalayan rain shadow where precipitation falls on the southern slopes leaving the area to the north relatively dry. After the first few days trekking you enter this area and remain there until south of Marpha (say). In contrast, the Everest Base Camp does not benefit from this and nor does Annapurna Base Camp.
Being summer it is warm even when raining at the altitudes where it rains (on the AC trek) and the typical weather pattern is clear mornings with cloud building up towards noon with rain spells in the afternoon and evening. Mountain views do get obscured by cloud but there is usually enough to satisfy and take photos in the mornings.
Some links:
Weather info for Pokara (close to the Annapurnas).
Annapurna map
Monsoon trekking blog where the weather was favourable (unlike my experience in the same area).
There are advantages too - it's out of season so the trails and lodges are quieter and guides and porters (if you will be using them) might be a little cheaper - as are hotels in KTM and Pokara.
Don;t be put off by the rain and I hope you enjoy the trek.
scoodly
