From long, and varied, experience I can say that nothing beats doing it yourself.
There are services available that will do some, or all, of your planning/filing/booking but they come at a price (generally cost plus) and are usually of the "garbage-in-garbage-out" format. You tell Jepp or Universal (etc) where you want to go and they send you the package and a bill.......what they won't do is tell you what the options would be; with their various costs and complexities. So if you don't know where you are going, you won't know what is good planning. If you know what is good you might as well do it yourself........
I have seen quotes and routes prepared on this basis and the cost made me wince while the route made me laugh. Technically the stops were fine, routes OK and valid, leg distances sensible, handling agents appointed. But they had just drawn a line on the map with no regard for how easy (friendly) a stop would be or how the costs compared to alternatives. Making a dogleg or avoiding certain countries could save a lot of dosh as well as plenty of hassle.
They are also pretty jet-centric and avgas is not freely available in many places. I'd always rather check myself than be stranded.