Round takes tighter curves better but otherwise, they are pretty comparable. If exposed to sunlight - laid on top of the soil - the recycled rubber hoses last about 3 years. If covered in mulch, maybe a couple of years longer.

You shouldn't be able to see water spreading very far from the hose on the soil surface - just a few inches, if that. The soaker should just sweat water......no discernible drops or any spray. It is how the water spreads under the soil surface that is of importance and that can be significant depending on your soil structure. You want to run the hose for a long enough period of time so that the soil is evenly moist down to 8-10". At that depth, it should have spread out at least that far, if not quite a bit further. Imagine a cone with the apex at the soil surface and the base down at the root zone.

I prefer round for more even watering and less waste. The flat acts more like a sprinkler rather than a soaker if you place it with the holes up and tends to spray out over a wider area but it also wets leaves, waters more shallowly, and wastes water.

When you place it with the holes down so that it acts more like a soaker hose then the small holes in it tend to get plugged easily.

Dave