All I used was army ponchos for twenty years. For general backpacking and camping, IMO they are superior. They are cheaper, they actually are more airy than rainsuits made of any material, Gore Tex, eVENT, whatever. When you push it hard on the trail, you are going to sweat like a pig no matter what you do and with rainsuits, its harder to stay "aired out" on the trail.
For me, I found Gore Tex rainsuit to be particularly intolerable during the rains in the hot summer. Id rather have a poncho.
Another advantage of a good poncho is that you dont have to carry a waterproof pack cover. You just throw the thing over the top of your pack and walk. That saves a little weight.
When buying ponchos, avoid the ones made out of vinyl...they are waterproof but cheap and tear easily, as well as uncomfortable next to the skin. The vinyl ones are OK for stationary camping, but not backpacking.
I just wish the US military still issued a poncho like they used to issue...they had like a rubber type coating on them...they were awesome...best poncho ever made. Probably a little heavy by UL standards, but those things worked.
I dont have a clue what modern brands of ponchos are really waterproof versus "water repellant" or "water resistant." Vinyly is waterproof, but those are the cheapo crap ponchos you dont want to buy. You want one that is totally waterproof...non-breathable, but of good quality.
Good poncho plus Gore Tex lined boots is a good combination for walking.