I own a Tanaereva Cr and without any minor doubt he's my seconf favorite card on the game, just slightly behind Lamar Cr. Tanaereva Cr fits in every deck, he's the strongest card of his clan and his price should be a lot higher in a year, or less. Still not overpriced as Lamar Cr or Vickie Cr, pick it up or leave with no man, he'll do your hard work because he's that good.
Caelus Cr, is a good choice if you use Skeelz and you plan to continue with them, but if you want to really be "OP" and have a monstrous, bloody deck, Tan man should always be your first option. I'm going to depict a quick battle between Caelus Cr and Tanaereva Cr:
Caelus = 4/8 -5 Power points opp. min. 2 VS Tanaereva Cr = 5/7 -2 Damage points opp. min. 2 (With his bonus activated, he becomes a 10/7 but when his power is reduced by Caelus's ability, he stays as a 5/7).
See? Tanaereva Cr is stronger, and far more diverse and intimidating as one would say normally of a card. For me, Tan man gets its place on my deck, but it's your decission. Good luck.
It's up to you really
which one do you want a Skeelz deck or Ulu Watu deck?
Tanaereva Cr is more of T2 card than T1
caelus is more of T1 (even though he could be used as T2 card)
Ulu Watu T2 deck is definitely one of the best T2 deck you can get (with tana, Wee Lee, Stanly, etc)
you can't say caelus is better simply because he can obliterate any 7 power card
13 power tanaereva will make any opp scared and usually give up (or overpill and get their damage reduced)
They are both excellent cards. I would say it depends on your playstyle. Tan man is terrific, because he is useful in absolutely any situation. Caelus can be used to overpower certain cards, and therefore can sometimes limit the choices your opponent can reasonably make. If you prefer to win by adapting to the events of the match, Tan man is "better." If you prefer to win by forcing your opponent into a difficult situation, Caelus is "better."
One thing to consider is Kate's tax. If you miss having Caelus Cr and decide you want him back ASAP, you will lose a non-trivial amount of money. If you're not the kind of guy who cares about collection size, I would recommend selling or trading some expensive cards from a clan or clans you seldom use. That way you won't have to choose between two great cards.
Tan Man is better at being an overall more threatening, any round card who's skillset is very diverse...ie: Can bluff/block/hit
Caelus is better at beating cards at with little pillz...ie: A simple 7 powered card will have to double the pillz you use on Caelus to beat him...however he has many more counters than Tan Man...Solid attk manip/Full stops/ Protect:Power etc etc
Id say Caelus acts more like Spyke...forcing your opp. into a *Wow I can't beat his 6 pillz Caleus with any of my cards..at all...with all my pillz...I lose* especially since Skeelz has so many defensive walls..whereas Tan Man is a *Oh crap, a 10 powered 7 damage DR that I can't really do anything against except Dr'...crap*