a 200W heater should be fine, depending on how cold your place gets in winter (you can always get a larger heater like a 250W or 300W if you really wanted to) --> here in NC, it doesn't get too cold in the winter, so I can get away with "less than recommended" heater strengths.
As far as comparison is concerned, it all depends on placement. The inline heater will have water going over it continuously; the submersible would need to be placed in an area of high water flow, like near the intake or return of the filter, for it to perform really well (of course, if you keep it at the opposite corner of the tank, that side may be a degree or two warmer than the other side of the tank).
I've never used inline heaters (only have ever used HOB filters or sumps), but the people that use them typically have good things to say about them. For submersible heaters, I currently have an EHEIM Jager in my discus tank and it works really well. I also have an Aqueon Pro in my blackwater tank. I like certain aspects of both, but if I had to pick one, I would lean towards the Aqueon (plastic casing = pretty much impossible to break). It also has an LED that will go from red to green when it's done heating, which is a nice feature