Misty, for sure.
Misty was amazing, I don't know why so many people ship May/Dawn with Ash. No hate against your ships, just my opinion, but the chemistry they had was beautiful.
I may be biased as the old anime is my favourite, but I think it all depends on how they first met and Misty was the perfect person to be with Ash - she helped him so much throughout everything c:
Aw, I miss Misty!