Not wishing to high jack the thread, but how is the Yorkshire three peaks challenge harder assuming both are completed withing a 24 hour time frame. I have done neither challenge, but I have climbed all of the peaks.
Typically the N3P is a '24 hour challenge' and a significant aspect of that challenge is on your driver. It is absolutely trivial to bring a friend who drives at 90+ between the peaks, dodges speed cameras, and gives you a massive time advantage on the hill if you are rigidly sticking within this '24'. This will also leave you significantly fresher than those in buses. Realistically, because minibuses have a speed limiter, what you end up doing is looking at time on the hill and then extrapolating your driving time to call it a '24 hour challenge'. Drivers should never be in a position where they are pressured to 'make up time' for the group.
If you're walking (and you shouldn't do both) you'll spend around 13 hours of that on the hill. The fundamental differences are that the N3P is divided by 4-6 hour minibus rides between the peaks - so you're only ever exerting yourself for a single ascent at a time (so 4-5 hours effort, probably more on Scafell if you go via CR) before getting to go downhill again. If you're not terrible doing ascents then this 24 hour challenge should be doable provided you have a group who have themselves organised and don't take undue stops on the hill. Ben Nevis is pretty easy via the Tourist Path (you're basically doing a lot of stairs) regardless of the weather, as is Snowdon. After BN you get a nice long rest, a stop at services, restock on some food etc. The Y3P on the other hand doesn't have this component if you want to aim for the 12 hour time (as a walking challenge for non runners).
From my experience leading I'd say you need to be in better shape to do the Y3P because some people really start flagging in the 2nd half whereas most people have enough glucose (and can replenish it between the hills) for a big effort for each ascent before having gravity assist them on the way down. The N3P however may be grim for you if you're unable to sleep on a minibus or get travel sickness. The mental aspect of being awake for 22 hours and then beginning Scafell Pike in the dark is sometimes a little much for some, and these some less determined competitors take this opportunity to stay on the bus. For Snowdon in particular (when you've been awake for 26hrs+) it will be mentally difficult for some to put the waterproofs back on even if it is by far the easiest of the three hills.