First off welcome to the Waze editing forum.
Just to be different I prefer the A414 :roll: but sometimes find when travelling in the opposite direction from the western side of M25 to the A1 Waze will suggest staying on the M25 right up to the A1, this adds around 5 miles to the journey and is rarely quicker however using the A414 does add 5 roundabouts so it’s personal preference. The only time I’d stick on the M25 / A1 route is when driving a horsebox as it gives them a smoother ride, the wife’s horse tends not to like the way I take roundabouts. :lol:
I’m surprised you want to avoid the A414 when travelling south, I always find the A1/M25 / Bignells Corner roundabout to be dreadfully slow in that direction due to all the traffic lights, even Google Maps suggest avoiding it as it adds 5 minutes to the journey without traffic.
To answer your question I would do as Dave has suggested and look at the alternative routes, I often do this several times throughout my journey and view the routes in Map mode so I can select my preferred route based on time and distance.
I’d avoid Dave’s second suggestion of adding a ‘go via’ as this wont take account of traffic, Waze will take you via that point even if it takes all day!
As to can you change Waze’s default routing, well Waze will prefer to use motorways and major A roads but as the A414 is a major road that is not going to help. Waze will prefer to stay on the same road within reason and avoid junctions so from that point of view it should prefer the motorway but that has to be balanced against saving 5 miles by using a major road rather than a motorway, so that probably makes it even. In this situation I believe the major factors Waze will take into account are the time and distance, distances obviously for the two routes are fixed but the times will vary throughout the day.
On major (busy) routes we believe Waze records each individual segment times in 15 minute intervals for each day of the week so 8:30 am on a Monday morning will be different to 01:30am on a Sunday. Note a segment is between any two road junctions in Waze so A1 J3 at Hatfield to M25 roundabout is two segments (you pass an on slip at J2) but the Bignells corner roundabout and slip roads add a further 11 segments. In theory you could influence the segment times by driving your preferred route very fast and the alternative route very slow but due to the ammount of traffic you would have to do it many times in each 15 minute time segment :roll: and to make it even harder to frig Waze is not only looking at historical times but also live traffic.
That takes us back to asking Waze to calculate 3 alternative routes BUT to get Waze to look at the difference between using the A414 or the A1/M25 you would need to select a destination not too far past the point where those two routes join. If you were travelling to the tip of Cornwall from Stevenage the three routes Waze would probably suggest are M4, M3/A303 or A30 all of which are from the western side of the M25, I doubt it would offer three different routes to the get to the M25. Whereas if you enter Heathrow as a destination it is more likely to show the two alternative routes that you are interested in using.
Interestingly I have just done that and Waze still prefers the A414 and doesn’t offer the A1/M25 option, there must be problems on the M25 between J23 and J22. Currently the two alternatives are either to work your way over to Luton via Hitchin then join the M1 south to the M25 adding 11 minutes / 7 miles to the A414 route OR use the A1 south past the M25 to Mill Hill then join the M1 heading north from Edgware which adds 12 minutes / 8 miles to your route.