I like the double layered "Aikido" trousers from both Tozando and Minamoto Shokai. Both options seem to be pretty resilient and I've never had mobility problems with them. Just remember, even though they say "pre-shrunk", they will still shrink (usually quite suddenly after the 5th or 6th time through the wash), so consider buying one size longer than the measurements seem to indicate.
GTMA (Golden Tiger Martial Arts) double-layer judo pants also seem to be decent. However, last I checked, they only come in a set with their double-weave jacket, and that jacket is a bit overkill, it's very heavy and stiff! I will not
recommend the GTMA trousers that come with their single weave gi set, as the fabric is a bit fragile for aikido (once during a seminar, I had a nearly new pair start to split in a rather embarrassing location).