I've installed my fair share of led gu10s (I'm a sparks).

My experience has been that lads will be recommending this that and the other but no matter what they cost if the casing is made from plastic they won't last. They need a decent heat sync for longevity and the best ones will have a metal casing with fins which will act as that. If you buy in bulk there will nearly always be one or two duds no matter what make they are.

Personally I would go to a wholesalers and look at the fittings before you buy them, you might be able to swing trade price for a bulk purchase.