Right now G2 appear notably better.
Heroic were 7-8th at Blast World Finals, while G2 won it, though that's forgiven because of Konfig being subbed for Stavn.
Heroic also struggled at Blast Spring Groups, losing to EG (!!!) and Vitality outright, while also dropping maps to Astralis, BIG, and EG (in their second Bo3). Heroic lost a map to coL here at Katowice as well, though they've looked improved since that opening Bo3 and not dropped another map (and demolished Vitality in the group final).
Meanwhile G2 went 6-0 in Blast Spring Groups over BIG and Navi (twice). They won Blast Global Finals, only losing their opener to FaZe (and have not lost a Bo3 since at 10-0). In fact, G2 lost only one other map since the FaZe match, to Vitality, in overtime (meaning they could've 2-0'd both FaZe and Vitality under the right circumstances). Here at Katowice they are 6-0 again heading into playoffs.