What is the consensus on cables. I see three options
Conventional cables maintained well maybe with middleburn oilers.
Fully sealed systems like ride on
Running a full length outer.
Never tried fully sealed, worth the money? Any thoughts.
fully sealed is really full length outers for frames that aren't drilled for it.
Full length outer is probably cheaper.
Full outer on my Hardtail (frame lugs designed for it). Definitely runs more reliably and needs fewer cable changes. Thinking of drilling out the stops on my FS to do the same.
I just use Shimano XTR/SP41, with the wee sealing ends, and cheapo stainless inners. Last for a very long time, and cost almost nothing to replace the inners. The outers tend to outlast my frames 
Even if this only lasts half as long as a top quality option, it costs less than half as much.
As for what format/layout- whatever the bike is built for. Which means full outer on a couple of mine, split outer on others. Seems to make absolutely no difference- I can see why it should, but in reality not so much.
Had a look at ride ons £40 odd notes for a gear cable seemed steep. I ride in all weathers and I need a solution to this as my shifting was right up the shitter after one very wet muddy ride.
I guess this is slightly OT but .....
I have found running basic full length cables (jagwire etc) but before assembly dripping in a little chainlube to either end before assembly to help keep the water out and the cable running smoothly.
I actually found this set up smoother than my Gore sealed cables.
If you must use gear then full length SP41 and some teflon coated inners. Middleburn oiler ~4" from the end and replace the last 4" and the inner every so often.
Or just singlespeed it
For me the setup below has worked VERY well in the last few filthy rides this month.
SP41 Outers.
Sealed non-tongue ferrules on first outer section (shifter to downtube)
Sealed rubber tongue ferrules on middle section (under BB).
1 sealed rubber tongue ferrule / sealed ferrule on rear mech section.
Shimano PTFE coated innner wire.
Cable oilers on the longest outer (from shifter to down tube))
Lubricate with Finish Line Red Teflon lube.
Middleburn oilers are the key to slick cables. I've also got the XTR/SP41 outers, sealed and tongued ends and black PTFE inners but when the inners need replacing I'll just use normal shimano stainless.
Oh, regular cleaning and lubing in foul weather is the key here. So take the outers out of the slotted guides and clean and relubing makes an improvement.
Dont get Clarks SS inners, as they are noticeably rougher then std Shimano SS inners.
Another vote for XTR here, with (very) occasional maintenance. I run them full length to my Avid disks.