Service parts: OE or aftermarket?

My D2 TD5 needs a new clutch slave - at least I hope that's all in needs..
What is the difference on parts such as these between aftermarket and OE? Should I buy a cheap anonymous AM (which I assume will be Chinese) or a Lockheed at twice the price?
Are there AM brands to avoid? Is Lockheed better than Lucas? What's the general opinion on AM versus OE?

if the jobs a nightmare to do or safety related then OE every time.

have a search on here for "britpart" then make your choice

actually, feeling generous, here's the link:

http://www.landyzone.co.uk/lz/f16/big-debate-britpart-s-tpart-102232.html

I use LR direct alot, you can choose your brand of aftermarket, or even distributer of OEM, only downside to them if you have to know your part number.
OEM everytime unless im really strapped for cash.

Cheers chaps. Lockheed it is then.

I usually try and avoid Britpart and go for a famous name brand that's midway between Britpart and Land Rover's own. So Lucas, Lockheed et al should be fine. I fitted a lot of Lucas TRV stuff when I rebuilt my brakes around a year and a half ago and all seems well so far.

Almost everything I have fitted to mine has been Brit part (mostly accidents) and as yet they have all been fine so I can't fault them but you do notice the difference in the quality

Sadly I've often used Britpart with no probs, then had a brake master cylinder that literally lasted 3 months...... its the failed one we all remember longest of course......

LR genuine is often silly money (tho not so much for Defender bits), but if within reason I'll go for that. Otherwise well known independent mfr - Lucas, Lockheed, SKF etc etc. A