Heading to Ronda from Seville best route to take

Easiest will depend on where in Sevilla you start - picking up your car at the SJ station, airport, bus tetminal or south? That will vary the best route out of the city itself.
Otherwise, whatever route, you'll likely end up on the A374 to get into Ronda.
Most routes from Seville will only take under 2 hours, so I'd plan your's based on (where you start and) what you want to visit along the way. All routes have scenic views so I'd add at least one break to visit a village along the route if you have that time.

Thanks Nick we are staying in
Montequinto, Sevilla.

If wanting to make an entire day trip out of it and if you wanted to see some villages en route, you could head south taking the A4/N4 or the toll road AP4 to Arcos de la Frontera. After it, head east on the A372 towards Grazalema, or the A384 towards Zahara de la Sierra. From either of those Ronda is a short drive away.

A more northern route, you could take the A360 towards Morón de la Frontera, then the A406, then A363 to Olvera for a stop. From it, take the smaller roads CA9106 and CA9120 to Setenil de las Bodegas for another stop, then on to Ronda.

It all depends on if you want to make any stops along the way and which places you want to visit.

Thanks I think 1 or 2 stops along the way. Will,look at the towns you mentioned.

In Sep 2023 we drove from Seville to Ronda on an easy route we chose, stopping at the Oleum Viride olive farm (with a gorgeous view of the village of Zahara de la Sierra -- one could skip the olive farm and just stop at Zahara), Setenil de las Bodegas, and -- just before entering Ronda -- the Mirador La Hoya Del Tajo viewpoint facing Ronda’s Puente Nuevo bridge (https://maps.app.goo.gl/Y44seNa3LYjMQRq3A). More info and links are in our trip report (part 3): https://community.ricksteves.com/travel-forum/trip-reports/trip-report-spain-aug-sep-seville-ronda-granada-cordoba-madrid

GeoffB thanks for the info did you have issues parking in Sentenil de Las Bodegas?

If you are starting in Montequinto then you already have the advantage of being south of the city centre and not needing to fight traffic through or around Sevilla. A "straight shot" from there to Ronda is about 90 minutes.
I'm not sure how much time you actually want to spend on the journey, but if one or two stops, you could stop first at Utera. Then go onto Olvera and/or Setenil de las Bodegas (the two are only about 15 minutes drive from each other).
Parking is available in all these places, although you may need to walk a few minutes from the car park to the heart of the town/village centre. For me, it is usually easier to park a little out of the town centre and then walk, compared to trying to drive along the small central streets which, in theory, could get you a little closer parking.

Thanks no problem on walking just don't want to navigate the small streets

GeoffB thanks for the info did you have issues parking in Sentenil de Las Bodegas?

I had no issues parking as I used the "Parking Los Caños" parking lot. From there it was about a 5 min walk into the heart of the village.