Malco Eagle Grips are the pick for best overall. At $35 and made in the USA, they finished first in all four grip tests, and not narrowly: 1,250 in-lb on a soft grade 2 bolt, 1,110 in-lb on a grade 8 bolt, 222 in-lb on the front teeth alone, and 410 in-lb on a hardened tool steel socket extension — enough to leave marks in the extension itself. The pinned and braced upper jaw, the power ring and genuinely sharp teeth all show up in the numbers, and the adjustment screw is the smoothest of the eighteen. They take slightly more effort to unlock than the easiest pairs at 8.1 lb, which is the only real cost.
The Irwin Vise-Grip is the value pick. At $26 it placed second in every single grip test — 1,129 in-lb on grade 2, 913.6 on grade 8, 169 on the front teeth, 308.5 on hardened steel — with teeth that came through the hardest test undamaged, and it releases with just 6.9 lb of force. Anyone unwilling to spend up for the Eagle Grips loses very little here. The $20 Craftsman with straight jaws is the other strong buy: third on the grade 8 bolt at 772.5 in-lb and third on hardened steel at 284.8 in-lb, with an easy 8.3 lb release — fourth overall.
Below about $15 the picture turns ugly. The $7 Pittsburgh never generated enough clamp load to register on the tester on any of the three bolt and steel tests, and managed only 13 in-lb on its front teeth; the $9 Harden was little better and its adjustment screw pulled out of alignment with the connecting rod once torque went up. Price alone is no guarantee either — the $48 Gedore and $33 Grip-On both have adjustment screws that will not turn freely, which caps clamp load no matter how good the jaws are, and both bent or trailed the field under load. The $27 Knipex, from a brand that usually dominates these comparisons, warped visibly at 180 in-lb of adjuster torque. If a single spec is worth checking in a store, it is whether the adjustment screw spins smoothly.