I have some good looking loops here, not practical loops, too difficult to tie
A good-looking loop, would, most probably, be proven to be a practical loop, too...
Why am I saying this ? Because a good - looking loop would be a simple enough loop, so we it can be easily remembered and tied. We do will never characterize as "good-looking" an amorphous mass of tangled ropes !
A good-looking loop would retain a certain fluidity of lines, so the rope path would not make tight, abrupt U-turns. The eye likes to follow a smooth curvilinear path, without any ugly acute angles or protuberances. The eye knows much the brain does not realize at once...
The first loop presented here is definitely good-looking. It is a two-collar "Eskimo"-like bowline, which means that it is a secure loop. I believe that, when we are talking about a "secure" bowline, that can be used for rescue purposes, for example, we should always mean a two-collar bowline. I have not seen a bowline on which a life can depend on, that has only one collar. It may be a matter of psychology only, true, but psychology plays a major role in such circumstances - in relation to the rescue personnel as well as to the victims. In boating and other not-so-critical uses, where the material is not-so-slippery, the use of a two-collar bowline may indicate ignorance about the marvellous effectiveness of the nipping loop+collar mechanism of the common bowline, and the insecurity and fear that stems out of such an ignorance...
What I would like to see in a secure bowline is a nipping loop encircling three rope diameters. Not because the segments of the rope are better nipped there - they might well be nipped
less tightly - but because the nipping loop itself takes a rounder and wider form, which means that it is more evenly tensioned, and stronger.
The second loop is similar to the first, and one may even say that it is more secure, because the tail is squeezed by the eye-leg-of-the-bight in two distinct points ( at the first loop, it is adjacent and runs along a long segment of it ). However, I think that, at the first loop, the eye-leg-of-the-bight of the bight follows a smoother, easier path as it enters into the bight - that is why I would prefer the first from the second loop.
I do not like the other loops, for a simle reason : I do not like the abrupt turn of the rope at the 1-rope diameter collar around the eye-leg-of-the-standing-part. It is
not good-looking !
I have many ropes that will not turn around a 1-rope diameter curve, if they are not tensioned very hard. At this point of the knots, this second collar will remain loose, unless the knot is tied on a very soft material. Who likes voids in his knots ? ( Nature does not !)
The last loop belongs to a slightly different breed. I do not see the point of the second turn around the rim of the nipping loop - without it, the loop would belong to the family of the Janus (two-collar) bowlines, which are already very secure, without this additional complexity.