Crash, by like a million miles. The difficulty in 1 (and 2, to a lesser extent) can be a bit ridiculous at times. But, that's what gaming was like in the 90s. And Crash is just a great video game character. Spyro is more generic, and while a decent series, just doesn't have the overall awesomeness or hold the same significance in VG history as Crash Bandicoot does.

In the interest of full disclosure - I have played a lot of the N Sane trilogy, and not a lot of Reignited.  

Crash, and anyone who answers otherwise is dead to me.

I will say though, I think of all six games I do love Crash Bandicoot 3 Warped the most, more than any of the Spyro games.

It's less punishing than its predecessors and has the most variety.