When we went searching for a cot, we had two criteria. 1. We wanted it to have a drop-side 2. We wanted to have a mattress that we could adjust the height. Two years later I can tell you having both of these features has really more to do with gadgets for the guys that any real benefit. Let me tell you why. You simply do not need both these features. The adjustable mattress height means you don't bend too far down to pick up the baby when s/he is a newborn. As the child grows bigger and you have to lower the mattress height the child stands up to be picked up. The drop-side is a pain as it is hard to lower when the baby is in your arms.
So when you buy a cot, the adjustable mattress position is more important than the drop-side. Spend your money on other things.