I'm using
Endura, waist longs, no pad.
Features affecting choice:
Bib or no bib?
With some bib tights you've got to more or less undress in order to take a leak. Others are low enough to just yank down at the front, and a few have zips or clips on the shoulder straps. On the plus side, bibs are more comfortable due to the lack of a waistband, and they don't expose a gap in the middle of the back if your jersey is a bit short.
Pad or no pad?
If there's no pad, you wear a pair of shorts underneath. If it warms up during the spring and autumn you can take off the longs and carry on just in shorts (provided you have somewhere to carry the longs).
Ankles
Generally it's a choice between a stirrup and an ankle gripper (usually with a zip). Ankle grippers can fail to grip, and allow the bottom to ride up a bit, but on the other hand you can wear the longs on the outside of winter boots or overshoes. With stirrups you have to have the end inside, and if it's raining the water from your leg gets wicked in and you end up with wet feet.
Windproof?
Some come with windproof material at the front. It's warmer, but comparatively stiff and hence less comfortable. You also get sweaty more easily.