We can revisit this conversation if Bale can reinvent or rejuvenate his game for the next 5 years.
At their peaks, they are different players. Giggs was mesmeric and exciting to watch, blending pace and mazy dribbling few could. Bale's athleticism, pace and power in shots gives him more headlines in scoring in big occasions as a modern striker/winger hybrid.
As it stands, Giggs' renaissance from the mid 2000s into a CM that could still beat people while showcasing a creative range of passing, puts him in a different class to Bale.
If Bale can somehow overcome his glass ceiling (literal shortcoming of his injuries), I think he may have the tools to adapt and show his skillets beyond the athletic part - he is a class player. Giggs went through a transformation as well, from frequent hamstring injuries to a player that could last til 40, adopting Yoga etc to help. Bale may need to find a similar path, time will tell - pacy players are prone to those injuries/fading away from 30s (unless a freak like Robben)