King Alfred’s Way

I suppose it depends on the rider. I've done it 4 times now as it's ace. Each time on a gravel bike which for me, is plenty.

Perfect, that sounds pretty easy

I did it on a mtb with fast tyres and was glad of the extra cush. Obviously could have done it on slimmer but think I had more opportunity to enjoy the view on the mtb

I suppose it depends on the rider.

This is it really as i was happy on my short travel full suspension 29er...made the (many) downs more enjoyable and was kinder on my back on the hard summer ground over the couple of days

I did it on my mtb but a gravel bike would've been fine.

I've done it on both, in answer to the op''s question it is easier on a MTB, no question. It's doable on a gravel bike though. I would say it might even be more fun if not carrying camping kit on a gravel bike though. Loaded up a MTB would be my choice though for sure

I have the same debate as the OP, I have been wanting to do it for the last 2 summers but plans have been disrupted constantly. 

This year nobody is dying imminently or looking to frustrate my plans (yet) and a long weekend in June is now booked in. 

MTB option is rigid, 1x, 2.4x29” front/2.1x29” rear, but lacks barnacles for luggage. 

Gravel bike is 2.1x29” F/47mmx700 R (1.95” ish), 2x and has barnacles galore… 

I plan to camp so luggage capacity will matter. 

I have done it on a FS mtb not carrying luggage. It had pretty fast tyres. The longer road sections dragged a bit, but of course faster on the downs off road

The terrain is what i ride most weeks. For me 40mm tyres are just making life difficult, although that’s what lots of people use. I think a gravel bike with 50-55mm tyres is a pretty good compromise.

I did it a couple of years ago on a gravel bike with 42mm tyres, perfectly doable though some tricky sections. As others have said it'd be easier overall on something with suspension but the road/easier sections will drag a little more.

Depends what your MTB is. You could ride it on a CX bike on 33s but I wouldn't. It's not so much about the terrain as carrying a load. Maybe also about how long you intend to be taking to do the route. I think a rigid 29er on fast 2.3 XC tyres is perfect for things like this but I saw more people on gravel bikes when I did it. If I was doing sections of it on a day ride, sure. But not my pick for the full loop loaded up. 

In the heatwave last summer when the trail was bone dry I was very glad of having MTB tyres and at least front suspension.  My son took a bit of beating on his gravel bike.  I assume wet weather would actually soften up the trail but of course you'd then want decent grip. 

I rode it 2 years ago on a 29er hard tail with maxxis crossmarks and I was pretty comfortable. It was early May so no brambles etc but I remember thinking that the ruts and roughness of the ridgeway would have been uncomfortable on my genesis longitude rigid bike. 

Agree I could have done it on the genesis, but not having to concentrate picking the smoothest lines all the time made me look up and enjoy the scenery a bit more.

Maybe also about how long you intend to be taking to do the route.

That is a good point, I’m allowing myself 3 days, but the start on a Friday may be a little late.

The ambition would be to do it in 2 but I’m not sure my fitness or fatigue resilience will allow for that, I think to do it faster I’ll be bivying in ditches rather than posh camping or B&Bing. 

The trip I missed out on last year with mates they did it slow and pre-booked B&Bs, a larger part of me is into the idea of going lightweight and kipping in ditches. obviously I’m a different flavour of masochist to them, but the better plan might be proper camping in a tent with more kit. 

FWIW Whenever I rode the Ridgeway double, or an end-to-end out and back bivi trip, or on the KAW, I always hated my gravel bike by about 2/3 of the way if not before. Whenever I rode my rigid 29er (bigger rims and tyres, different bars and riding position, different handling) I liked how it carried speed over the rough ground with a load on. Gravel bikes make great road/lanes and the occasional byway type of tourers but they're just not fun for long days off-road imo, not fast either. And I seems to pack lighter than most, the more load you have the worse they are. 

a larger part of me is into the idea of going lightweight and kipping in ditches.

It's great and ideal for a hobo weekend. Not a hard route, decent variety of terrain, easy to get food and water and loads of bivi spots. 

No one’s mentioned 650b option, so I’ll be first - did it 2 years ago on my Open WiDe with 27.5 x 2.1 Schwalbe Bites and it was great - enough tyre volume to smooth out the rougher bits and not too draggy on the road sections