Which Electabuzz should I evolve?

Use SGPokeMap to find Electabuzz raids. Do them and Pinap the boss for more candy. Then come back when you have enough to evolve and power up the level 25 one.

If you need an electric attacker right now: Evolve the level 33 one.

If you don't need an electric attacker right now: Evolve neither, you can score a better one from raids/research/eggs.

I would do the first one. From your info I suppose you don't have that many Electabuzz candies and you can't reliably grind them. By evolving the second and powering up to level 33 costs 70 more candies. So it's 70 more candies to get an Electivire with 2 more hp and 0.75 more defense. It's not worth for me, so I would evolve the first one and keep the second till I have 100 candies again.

If you are a perfectionist, I'd suggest you evolve neither and wait for a better one.