For those who are unsure the basic distinction between these two very different types of machine are as follows:
Rotary mowers cut like an upside down Helicopter. They usually have one solid bar blade that spins at high speed under the engine ejecting grass into a box on the back.
Cylinder mowers have a front mounted cylindrical blade that spins and ejects grass forward into an open style grass box.
It is generally accepted that for the best lawn finish you will need to mow regularly and often with a cylinder mower. This can be as often as every 3 days in the spring. Cylinder mowers cut every single blade of grass with a scissor cut which is why they give such a good finish because this system is less damaging to the grass leaf. If required cylinder mowers can cut very low often as low as 6mm or 1/4"
Unfortunately cylinder mowers do not cope well with long grass, wet grass, or the dry "benets" that appear when the grass is very dry.
Modern rotary mowers do a very good job, especially if the blade is sharp, but they do always slash the grass, and this can be more damaging. The rotary mower is more popular today because they are so much quicker than cylinder mowers, cope with most conditions even the wet and give a very reasonable finish if properly maintained. They are also much less likely to be damaged by grit or small twigs going through the blade, and their maintenance costs are usually lower.
Rotary mowers generally don't cut much below 30mm 1 1/4"
So if you want the perfect lawn, then a good quality Cylinder mower is the first step along with feeding, weeding, scarifying, watering, rolling.........................basically a labour of love.
If the lawn is a chore to be finished then choose rotary.
If you are somewher in the middle then consider a rear roller rotary mower. Remember it is the roller on a mower that creates the stripe, so a rotary roller machine will give you the traditional finish without some of the effort involved with a cylinder machine.
Remember also that many cylinder owners also keep a rotary mower in reserve for the wet cuts, or occasional summer cuts to get the dry storks.