I'm looking to upgrade my mountain bike and I would like to get something better than I have, if justified. I've never ridden any groupset better than alivio/deore, which work ok for me and have tolerated some abuse. I'm riding harder these days and I would like to know if a better groupset would be more durable. I'm not very concerned with the "bling" factor or the weight, just something that will stand some "serious" trail. Any thoughts? Please feel free to elaborate on the brand or isolated parts if you want.
Edit: I would like to make the question more specific, because my intention is not to start a discussion about Shimano or SRAM. I assume that both brands are ok. Let's see: I want the bike to do cross country but not downhill. When I say that I ride "harder" I mean that I've gone from following a trail to now jump, go over rocks, some mud, a bit of water, etc ... That has made my drivetrain to get out of tune and drop the chain frequently, even I if adjust it before every ride. I am discarding here my shifting technique as a source of problems because I know how to shift correctly. I thus want to know at which level of the groupset hierarchies (no matter if it is Shimano or SRAM) this is less frequent. That is, that you adjust the gears and they stay adjusted for more than a ride even after some abuse. If I am going to need to adjust the gears every time no matter if the group is a XTR or a Acera, well, then I will rather save my money. But if XTR is stronger and stays tuned for more time, then I don't mind paying for the quality. I would like to hear from experienced riders if they noticed (or didn't) a great improvement in reliability (not weight or coolness-factor) when they bought a more expensive groupset. I hope that the question is clearer now.