Aran Fawddwy is one of the big hills south of Bala and a good choice if you want Eryri walking without the crowds of Snowdon. The routes are serious enough to need proper weather judgement, but the reward is a broad, quieter mountain day above the lake country.
This is a fair-weather walk for prepared hikers, not a casual town stroll. If cloud is low, stay near Llyn Tegid or choose a shorter valley route.