There are basically two ways to comment.
The 'correct' way is to always use comparitive terms.
So taking aussie's example,
I place this ram in first place. As he walked out he caught my attention instantly and I was then directed to his tremendous thickness, depth and length. He carries himself well and shows fantastic development.
In second place we have a ram that is also very thick, deep, well developed and also carries himself well but I just feel he hasn't got the length and presence that the ram in front him does."
It would become
The ram in first place is the most eye catching ram in the class, he carried himself round the ring and has the best development of all the rams in the ring today. He is a thicker, deeper and longer ram than the rams below him.
The ram isnt as long as the ram above him, however he is much thicker and deeper than the rams below him.
etc
In reality, that kind of talking begins to get very stilted, so most people dont comment like that. Most people speak descriptively, like aussie's example, rather than comparitively. I like to use a mixture of the two and if I judged the class it would probably be:
The ram in first place today caught my eye as soon as he walked into the ring. He is a clear winner for me today, he displays amazing growth and development compared to the rams below him, he is a thicker, deeper, longer and generally a more muscular ram.
The ram in second place today again is a very thick, deep and well muscled ram, very similar in type to the ram above him. But I felt he lacked length compared to the ram above him, which is why he is in second place today.
The ram in third place which not as powerful and muscled as the rams above him, is a very long ram with excellent feet and legs. It is his structural soundness that placed him over the ram fourth place.
The ram in fourth place is a very well growth ram with well muscled rump, however I feel his is not as structurally sound in the hind end to be placed any higher today.
I also like to state the type of thing I am looking for in the animals, I usually state that at the first class of the day. So with beef cattle it is something like this:
When I judge my young females I am looking for three things: Firstly fertility traits, I need that female to go out there and produce calves for me. Secondly, structural soundness for longevity, I need her produce a calf for me every year for as long as she can. And the final thing I am looking for is carcass attributes, because after all, we are in the beef breeding business.
Bottom line is, speak however you feel comfortable. Dont say 'last'. Try to say positive things about all the animals, but at the same time dont be afraid to give negatives about the animals either. I HATE judges who will only say nice things about the animals. When my heifer is in fourth place I want to know WHY she is in fourth, instead of first or second or third. Without criticism, you cannot improve on those animals.
Communicate with your stewards and with the handlers in the ring; make it a friendly and relaxed environment. No one likes a judge with a stick up his butt. It gets the exhibitors tense, and then the animals get tense, and they wont show well for you.
Do it how you feel comfortable - I have seen a judge who wears a microphone and comments the whole time he is judging a class, so you get his thoughts throughout the entire time. Its very interesting, hearing him mulling over his thoughts. I have seen a judge carry a notebook and jot down notes.
If it helps you, pull the animals into line in the order you are considering, then ask for them to be walked again. Change it around if necessary. Walk them again if need be. It is your showring - take your time - but then again, dont take too long. lol
Trust your instincts - usually the ones that catch your eye are the good ones. For your first look at the class, get as far back on them as you can.
And if you have a hard time picking between two animals - ADMIT IT. When you place them, state in your comments "I had a hard time choosing between these two animals. I think I could place them either way and I would be happy. Indeed, another judge, another day, they might stand differently. However today I have placed the heifer on top for just carrying herself round the ring with a little more balance than the heifer below her."