All PC brands have relatively poor support and customer service; if you care a lot about these, spend the money and get a Mac. And I say that as a PC user.

Model matters more than brand for quality; buying a slightly heavier and more expensive business-line machine is generally going to get you something much better than a maximally-light model, or a lowest-priced consumer model.

Dell has the least-bad combination of service + warranty support on the PC side of the industry, but it's a low bar. If you don't mind paying for the better grade of service ("ProSupport" + Accidental Damage service), their service+support is still not up to Apple's, but almost pleasant to deal with.

If you can tolerate a compact 14" model rather than a 13", Dell has some wicked good (< $600) deals on the E7440 and E7450 refurbs. They have same warranty as new, and tend to actually have fewer issues than new because the post-return quality control is better.

With Windows 10, you can do a "reset" as soon as it's booted up, and get rid of bloatware that way. It's much nicer than on Windows 7 or earlier where you had to do a reinstall by hand.

Depends on the model; for a consumer model or one bought from a third party, I'd probably get SquareTrade. For a business model bought directly from Dell or Lenovo, I'd get their accidental damage service, and a warranty length to match your expected retention time -- although most of the business machines have a 3-year warranty to begin with.

Given your expressed needs, I would not wait for Skylake; the incremental speed and better video over Broadwell (and the unavailability of quad-core models on Broadwell) is unlikely to matter for you, and whether there's any appreciable battery life improvement is an unknown. It's also less clear which groups of chips will be included in the first release.

The first laptop Skylake chips are released sometime in Sept but I haven't heard a specific date, and the first machines should be available sometime within a month after that (although for build-to-order companies, there will probably be ordering within a few days of announcement.)

I've had Dell machines with their current incarnation of "soft interior" and it's not bad.

It picks up a bit of a shiny patina more quickly than a hardier matte plastic, and much more quickly than brushed metal as on Apple. If you handle it when your hands are particularly greasy it can leave a permanent spot. OTOH, it has not peeled or shown surface damage under normal use, and it held up relatively well to an (accidental) outright gouge with a screwdriver - the one spot that got gouged off showed the metal underneath, but the edges are still not peeling after close to a year of heavy use..

Build quality has always varied between lines. Which line of Dell did you have? Their Latitude line remains great; with the latest round of materials-cheapening on Lenovo's part probably the best business notebooks out there (although you pay for it in weight and bulk compared to other manufacturers.)

Lenovo also sells two lines. Most of their stuff is very good.

There's no relation between the XPS 13 (which is the newest version of a model that's been selling for several years) and the XPS 11 convertible. The XPS 13 has always been a bit overpriced (compared, for example, to similarly spec'ed ASUS Zenbooks) but it's been a well-made premium ultraportable all the way back to the early-2012 Sandy Bridge model.

They are clickpads, which have virtual buttons along the bottom edge. Which are, I should add, a bloody nuisance.

1) Discrete. Unless it's a very stealthy graphics chip.
2) Given his desire for "as long as possible" battery life and virtually no mention of performance, none of those sound like features the OP is likely to care about -- except maybe the number of ports, because that really is an abomination on the part of the new Macbook.

8gb is enough for the kind of use he talked about, HiDPI support under Windows is still somewhat iffy, and integrated graphics are only "slow" if you play non-casual games, do professional-grade video/photo editing, or do professional 3D work (in this last case, a consumer grade discrete graphics is only a little better, for lack of ISV certification and generally having gimped OpenGL.)

OTOH, for the OP, what about the Yoga 3 Pro? Nice HiDPI convertible, same Core M processor, at the high end of the price range but quite the nice machine.

I'd find both uncomfortably slow, even for general use, but the trade-off for battery life might be worth it for the OP.

Toshiba - haven't used in long enough that I can't comment on their quality; support is entirely 3rd-party retail in this country, essentially non-existant.

Samsung - their newer premium machines seem to be above-average in quality. Haven't used any of their cheaper models. Support is entirely 3rd-party/retail in this country, essentially non-existant.

Dell - quality on their Latitude business line machines is good (and has been), quality on their consumer-line (Inspiron/XPS) and small-business line machines (Vostro and "Latitude 3000-series" which is a recent rebadge of Vostro varies model to model but in general is a relatively poor bet. Support on the consumer side is poor, but at least offered directly. Support on the business side is poor-to-fair unless you pay for the upsell to Prosupport, which gets you a shorter queue and US-based support agents during the business day. Well worth it on a higher-end machine.

ASUS - quality on their higher-end Zenbook machines is above average. Quality on their cheaper models is poor-to-average, and best avoided. Support is entirely 3rd-party/retail in this country, essentially non-existant.

Lenovo - quality on their Thinkpad models, and a few other premium models like the Yoga are excellent -- arguably the best in the industry. Quality on their cheaper models is average, and probably still best of the cheapies, not that it's saying much. Support is about on par with Dell if you buy direct, and pretty much "you're on your own" if you buy through retail channels -- so buy direct.

HP - haven't used in long enough that I can't comment on their quality or support.

Their 14" models have shrunk with the last generation, and they've demo-ed a 15" model in a footprint that was smaller than their last-generation 14" -- so the odds of it are very good. If not, the next-generation (Skylake) XPS 15 might just be small enough for you anyway.

Processor-wise, no. OTOH, it might be worth waiting for the new models that come along with it, for exactly the reasons you just asked about.