Lesser Hiryus, Wild Tiger, Blue Beetle, Hiryus, Tsuki Wolf, Fire Beetle, Reptalon , 16th anni pony have panned out to be my favorite and most used pets.
The lesser Hiryu in the end becomes more versatile and an overall better pet than the Full Hiryu usually my first choice to take hunting. All of my Hiryus lesser and full get 120 parry 120 bushido 120 wrestle, anat and tactics and some I will burn Med, focus and resist scrolls on. Between 20 HPR and 40% Parrying they are almost unkillable. Throw in a AOE and Armor Ignore plus their natural with Bushido whirl wind and they are rideable. That makes Hiryus my top pick.
The Wild Tigers are just straight up brawlers and have the best Combat Graphic. They would be my first choice if they were rideable.
Blue Beetles while not my overall first choice, are my first choice for my tamer treasure hunter. The are tough and you can load them up with all of the greater and major chest loot to trash for points or drop off for unraveling for relic frags.
Hiryus make the list because while ultimately not as versatile in training as the Lesser Hiryu they have pretty colors and we all know pretty colors are more important than stats

Seriously though they are tanks and hard to kill.
Tsuki Wolves with their necro, Life leech and other attributes make them a must have in the stable for certain activities.
After adding taming to my miner the fire beetle at 5 slot allows me to mine just about any place the urge strikes me.
Reptalon while overall not thrilled with them, I finally found one that was able to be trained up to very good pet for some things I hunt.
The 16th anni pony, only being a 3 slot comes in at only 97 taming to use and control and by adding 70 taming and lore and jeweling it up to 100 on some of my fighter type toons the 3 slot pony has proven to be well worth 140 skill points and a couple of jewel properties lost. Durable hits hard and gives your PvM general purpose fighter type a lot more punch. The toon I run him most on is 120 Bushido 120 Parry 100 necro 120 swords 120 tactics 70 tame 70 lore with a high MR/MI/ Stam increase suit. The jewels are 15 tame 15 lore HCI DCI and 8 dex pieces . Proven to be a effective template for me and almost like swinging another weapon. The pony also doesn't require a lot of vetting with 20 HPR and all 80s primary resist and 45 cold. The pony replaced the armor plated pickle (Swampy) this toon used to ride.