UKC

I know that the answer is "how long is a piece of string" and "it depends" but could I have some recommendations to help me choose my next steed? Last bought an MTB 20 yrs ago and bikes have changed a lot. Budget £1K. NOT Electric as I wish to be able to maintain the bike myself.

I'm gonna be cruising Canal towpaths, easy trails, Long Mynd and possibly MTBO, Llandegla but would like to be comfortable enogh to get some distance in (30 miles)

The wheels do not need to leave/won't be leaving the ground as my creaky skeleton no longer bounces.

Thanks for your suggestions

I've not bought an MTB there but I have bought other bikes (mostly hybrid) and I would absolutely recommend Decathlon's own ranges (Riverside, Elops etc) as offering excellent value when it comes to bikes of all kinds.  For £1K there you should get something really very good.

Best to test-ride before choosing though rather than purely going off recommendations.

Give Beics Brenin at Coed y Brenin Forest a call and see what they've got available re. ex-hire bikes. Trek or Specialized. They're very well maintained and usually under 12 months old, lots of local bikers buy them. More bang for your bucks. https://www.beicsbrenin.co.uk/news/exhirebikes/

Bit like buying boots this. Go and annoy some folk in shops asking to sit on their showroom bikes and choose what feels best for you. 
Entry level Specialised or Scott might be worth a look. In Halfords, Boardman or Voodoo bikes get a good name for value.

Good luck. Buy a bike always brings out my most indecisive side!

Myfyr Tomos makes an excellent suggestion. The huge advantage with buying an exhire is that you can ride the bike for a few hours on proper trails. Sitting on in a bike shop is better than nothing but no comparison. My current MTB is an ex-hire and was cheaper than buying second hand. I simply hired for a day and they deducted the cost when I bought the bike.

One thing to note is that bikes have changed in almost every respect in the last 20 years. They are (arguably) much better than they used to be but are also much more focused and expensive. Unfortunately a single bike to cover both 30 mile rides and trail centre stuff will be harder to source than it used to be.  Modern bikes tend towards very slack angles (less good for comfortable mike munching) unless you go for a dedicated cross country bike- which will be aimed at racers and likely out-of-budget. Given your requirements you might be well advised to have ride of one of the more aggressive gravel bikes rather than an MTB. 

One last point: have you asked on somewhere like Singletrack? 

Having upgraded from my old 26" Marin I didn't think I wanted 29" wheels.

Having got them I am glad I did.  I don't miss the slight loss of precise handling and the bigger wheels just roll over much more stuff.

Voodoo Bizango was the go to budget hardtail for quite a few years and always got great reviews….I’ve ridden one and couldn’t fault it for the money!

The annual best hardtail selection (etc) from MBR is always a good starting point to see what is around:

https://www.mbr.co.uk/reviews/buyers-guide/best-hardtail-mountain-bike

If you then know what you are looking for and have some patience (and some trust in humanity), buying 2nd hand is always a good option. PinkBuke buy-sell is my go to for for buying/selling bikes and parts.

https://www.pinkbike.com/buysell/

There are a shed load of second hand bikes out there under £1k at the moment. Lots of orange P7s floating around on marketplace with some high spec components. 

Check out Winstanley's I got a Kona hard tail for around half price. Second hand bikes have to go a long way to compete with some of the deals around at the moment. Especially when you factor in the warranty etc.

That just drives the 2nd hand bikes price down and can make them an even better deal

[if you know what you are looking for and have some patience]

That was my point 😄, I've seen second hand bikes for more than the cost of a discounted new one.

Really does pay to look around.

I mean the prices at Winstanleys aren't great. On the low end stuff, sure they have some good discounts on stock thats a couple of years old. But they still want nearly £3k for a 2 year old Kona Honzo ESD. You can currently pick up a similar bikes with slack head angle, steel frame and a fox performance fork for under a grand on the second hand market.  

The difference between those sub £1.5k hardtails and the more high end "Hardcore" hardtails is just night and day. My Ragley Big Wig is probably the best mtb I currently own, I've done everything on it from multi day bike packing to big days out in the Lakes, The Borders and Wales. Picking one of them up for around £750 is an enormous bang for your buck in my opinion.

I got my Kona ESD from them for £1300 last year