So limited skins have been interesting through a lot of smite. The first two I can think of was caocaodemon ymir and poolseidon. At the time they were released they were fairly decent skins. ymir's was like a tier 2-2.5 by today's standards but at the time was fairly decent. Poolseidon always was pretty good and would probably be a decent tier 4 today.
The next limited skin I believe was the Infernal Agni skin that was pretty decent before being outclassed by swagni. Afterwards there was Archon Thanatos considered by many to be the best tier 5 skin.
Afterwards at the first summer of smite we were gifted with an space anhur skin that was pretty nice. had good effects on his pillar and stuff. Then at the second odyssey we got Sir Kuang a pretty good skin with a unique theme and an amazing ult, and we also got gundum thor. It tried something new but wasn't that well received.
Season 3 came in where we started quick with the rising dawn event giving us a limited Sol skin that hummed "what is love?". Then in the hell event we got a nox skin that had a nice effect on the voice pack and had a lot of red. Summer of Smite came in with merdusa which played a harp and introduced a special emote attached to a skin (not a god, that was geb). Then came a quick norse event where we got two ok skins with norse kali and chaac but they upgraded and had some nice particle effects. At the third odyssey we got some nice skins like old wa which wasn't limited, but we also got the tier-5 anubis skin which had a lot of special effects loaded onto it like setting the whole world on fire.
Finally we have Season 4 where the limited skins right now are. Green Morrigan, like Morrigan who is just wearing a green hood and dyed her hair red. Then Thoth who is a little robotic and is more electrical instead of mystical. I'm not sure if this is me being biased or anything but the current limited skins right now feel more like an additional tier 3 skin.
Oh yeah nearly forgot about pirate Susano (I guess it's fine for a pirate skin), and Wizard Guan Yu who is just magical. Really A+ on guan.
The event ending limited skins however feel so lackluster especially when compared with certain chest skins. DJ Zeus looks amazing, but was locked behind a chest. Doll Izanami is creepy and amazing but is locked behind a chest. Witch Aphrodite had neat cat splatting action… but was locked behind a chest. Seriously Hi-Rez are you putting every amazing skin in chests and only occasionally giving us a decent event ending limited skin once or twice a year?