Most companies wouldnt accept cheque and money order for less than 6 months, dont know of any that do it for monthly plans anyway.

A lot dont like paypal because they have to have an account there, even if they are just buying from you so although you can use paypal to accept credit cards, people still have to signup at paypal.
You might not think ig but a lot would just leave it if they had to signup with paypal before they can get an account which is why i think its also good to offer an alternative.
I use 2checkout as an alternative even though the fees are a lot more than paypal