IMO these dragons are mostly similar, and are good for similar jobs. They are primarily PVM phys-damage-tank type dragons,with one exception.
Knowing the skill caps is really important; I can't say as much about Dragon #2 since it's skills weren't posted.
Dragon #1 is a great all-around tank dragon that will have decent hit chance and fair Magic Resist. The high fire resist makes it your choice if you ever go to Grizzled. Dragon #3 is not a turd, it will have nice magic resist if trained up and very high damage in the fire breath due to it being at the extreme top end of HP. It's wrestling skill and magery skill levels are not distinctive, though, and its fire resist is the pits. Dragon #4 would do well being used to kill other superdragons, it's wrestling will go quite high, but Dragon #1 will be almost as good at it. Dragon #2 MIGHT be like this too, but without seeing the skills, can't say.
Dragons #3 and #4 have terrible energy and cold resist, this means that they will take significant damage from Cu Sidhes if they ever have to fight them. Dragon #2 is the exception in terms of its best jobs, in that it's resists make it better suited for dealing with cu sidhes, but it's wrestling must be decent or it can't work well (skills not posted on dragon #2).
They all have a nice, powerful fire breath attack due to the HP, obviously.
It's not always clear which dragon to pitch and which to keep, as dragons can be used for different things due to their variability. It's also not true that Phys resist is always the most important thing - - it's very important for many applications, but for others it's not as critical.
For example, one of my certain "keepers" only has 77 phys resist, 577 str, 515 mana, and his wrestling topped out at 116.8. His resist pattern, however, is:
77
90
55
57
75
and it's backed up by 941 hit points. It's a tank for elemental resists, especially fire.
This dragon is prime for Grizzled, he can stand right in the fire pools like a good Hiryu and be vet healed through it. I'm hoping to solo Grizzled with him soon (heh), I did Griz with a small group and he worked great for it. On the first Grizzled run, I took a different superdragon (my general-purpose phys which had 86 fire resist) and it was significantly harder to keep alive, I think he actually died once. You wouldn't think 86% vs 90% is all that big a deal, but it's evidently touchy when you have to keep something alive through that much fire damage.
