In terms of traffic all are busier in the UK but if you really want to get off the beaten track then consider option 2 and utilising either the Avenue Verte or Donald Hirsch's route.
1 London to Dover and then Calais to Paris.
Distance usually between 240 and 288 miles
The format is typically London to Dover on day one (80 miles), a ferry crossing to Calais and then cycle to Abbeville on day two (78 miles), day three features a flattish section passing WWI memorials and monuments alongside the River Somme en route to Beauvais (70 miles) and then it's the final leg to Paris (60 miles). The highest elevation is 751 feet.
There are plenty of choices on each part of the route too – for example if you want a less hilly section in England then look at the longer option which takes in towns like Whitstable and Herne Bay but stays north of the South Downs.
The ferry crossing from Dover to Calais is around 90 minutes - or let the train take the strain via the Channel Tunnel in 35-40 minutes.
Asked to nominate a favourite section of this route, Craig Wilson of Global Adventure Challenges told us: "The climb through the beautiful forest of Compiegne on day three is a clear favourite and if you go on our alternative route via Amiens then the castle at Chantilly is breathtaking."
2 London to Newhaven and then Dieppe to Paris.
Distance ranges from 178 miles up to around 294 miles
This is a favourite for those attempting London to Paris in 24 hours, with 59 miles to cover in England on the shorter option and then four hours of rest and recovery on the ferry before pedalling all the way to the French capital.
But don't think that 24 hour attempts are the only way to tackle this route as it actually lends itself to two fantastic and more leisurely options.
The first of those is the Avenue Verte which is a collection of cycle paths, bridleways, trails and minor roads which connect the London Eye with Notre Dame and was formally launched in the summer 2012 to coincide with the London Olympics.
In England the route mainly follows National Cycle Network Routes 4, 20, 21 and 2, heading through Surrey, West Sussex and East Sussex and including the likes of the Forest Way and the Cuckoo Trail which provide a combined 20 miles of traffic-free cycling on disused railway lines.
The downside is that it’s longer (100 miles from London to Newhaven as opposed to 59 miles) and some short sections use bridleways which aren’t always suitable for road bikes, meaning either a modified setup (wider and more resilient tyres) or hybrid bikes have to be a serious consideration.
In France, the Avenue Verte itself offers two alternative routes into Paris, the shorter of which goes via Gisors (150 miles) while the longer one heads through Beauvais (194 miles).
A shorter and arguably even more scenic option is provided by Donald Hirsch. In 2007 he created a route from Dieppe to Paris which has since garnered widespread acclaim as it stays on the quieter roads and tracks, and is fully suitable for road bikes.
Useful external links:
Official Avenue Verte site
Buy the Sustrans guide to the Avenue Verte
3 London to Portsmouth and then Le Havre to Paris.
Distance is approximately 200 miles
This is a similar distance to the Newhaven-Dieppe option (with a ferry crossing of just under six hours) and is typically done over 2-3 days (staying at Evreux for the latter option).
There's also a fourth option and that's going off-road on a mountain bike. An example of this is the British Heart Foundation ride which uses the Eurotunnel between Folkestone and Calais, covers 300km of riding and is almost entirely off-road on forest tracks, gravel paths and tarmac.