I had the same problem of desiding which on to have. In the end I chose the Simiyiar Light Freighter because it had a higher sale price and I'm currently 11mil richer then a was before. Don't mind me though, you choose which one suits your needs best.
Well, like the argument has been it's all about what you're looking for. If you're looking to be hauling more people, more stuff, be safer doing so with armor, and be faster, than go for the Simiyiar. If you're looking for a ship to better RP with, that has better weaponry to protect itself better with, then go with the Dynamic. What you're looking for in a ship is always the deciding factor for what you buy.
Personally, I would buy the Dynamic. I love the way that it looks, and I always have since KOTOR was a game I played every day of my life. I'm not a big fan of Mon Calamari ships, but that's just based on looks since its stats are quite good. When I buy a ship, I take a few things into consideration. One, I should be able to roleplay it fairly easily and fairly well. Two, I look at the max hyperseed I can get to in it. Then, I look at the arsenal that would be at my disposal for when combat is here and I may or may not need to protect myself. After that I check to see if it has escape pods or not, because those are always helpful. Lastly, I check the cargo stats. If a ship has all of the above, but its cargo cap isn't all that great, I may let it go. If it has a docking bay, that always adds onto maybe a smaller cap size and I may reconsider.