Lumens (ie how bright) output of a 50w halogen = approx 900. Lumens output of current LED replacements = 450, tops. So the answer is.. There aren't any, not if you're looking for the same level of brightness anyway. If you can live with less light, give them a go by all means. Don't forget to compare: Physical size (not all LED 'gu10 replacements' are identically sized, so not all will fit if space is tight) Beam angle Always compare lumens, not watts. Consider whether they need to be dimmed (not all LEDs are dimmable and those that are should have a new-fangled electronic dimmer, not the old-school type. The ones with a single LED are much better then the 'cluster' types. Light quality has definitely improved, even if the light output isn't up to scratch. Philips is a reliable brand. Buy the latest stuff, don't get fobbed-off with the backload of two year-old LEDs the bulb company is sitting on, which aren't quite as good. There are some new quite new ones from a company called ZetaLED which are meant to be good, but they are wide beam only. We have a few Megaman LED GU10s here (the 'best selling' one from BLT Direct) which are decent in light quality but only used for accent lighting. Buy they from BLT.. They have a very good no quibble return policy so you can try some out - and then send them back when you discover they're not bright enough.