I have played Hero system only as a supers game (Champions), but enjoyed it more than GURPS. It has more stats, which makes it easier for me to define the character that I want.
HERO has STR, DEX, CON, BODY, INT, EGO, PRE, COM, PD, ED, REC, Spd, END, STUN, and basic movement rate.
Equivalently, GURPS has ST, DX, HT, hit points, INT, Will, levels of Charisma, levels of Appearance, DR and limited DR, Fatigue recovery advantages, Basic Speed, Fatigue, and basic move. It lacks STUN. GURPS further has numerous Advantages and Disadvantages like Ham-Fisted or Musical Talent.
I'd say GURPS actually wins this one, handily.
Nope.
HERO has Advantages and Disads as well, called Talents and...Disads. Disadvantages in particular are open ended- there are some defined in the book, but several of those are actually mere exemplars. For example, the Vulnerability disad has several listed, but the sheer number of Vulnerabilities is limited only by imagination.
(I'm not familiar enough with GURPS 4Ed to know if it has a similar open-ended disadvantage structure.)
Then there's "package deals" which are GM/Player created groups of powers, skills, talents, disads, etc. that make one a member of a particular race, species, family, mutation type, organization, or other easily definable subgroup- like suffering from the long-term health effects from a disease or weapon, or perhaps a curse (like Lycanthropy or becoming a Wendigo).
At best, GURPS claims a draw here.