(i.e. no command opportunity, lower quality of officers and enlisted, fewer sea tours, dull work compared to the regular navy).
The vast majority of Supply officers go straight to sea for their first tour. Oh yes...you will be getting sea time in the Supply Corps. One of the cool things about Supply is that you can deploy to *anywhere* in the world. Supply is needed everywhere and at every command. You can't say the same thing for every other community.
Dull work? Well, that all depends on what interests you. As a Supply guy/gal, you are the go-to person. Someone will *always* want something and it is your job to get it. Excitement? Adventure? A Supply Corps officer craves not these things. If all you want is killing, spying, and destruction, I suggest going NFO/Pilot/SEALS/EOD.
Supply is for people who are business-minded. It provides a MASSIVE advantage for those who get out and seek a business career as a civilian. While your Navy SEAL gets out and jumps at a $40k job as a SWAT dude, your typical Supply Corps officer will get out and make double that, and possibly way more, if they apply their talents properly. You can walk out of the Navy with an MBA paid for by the Navy if you go Supply Corps. Combine that MBA and the practical experience of operating with multi-million dollar OPTARS will earn you HUGE paychecks on the outside when you get out. I say - Take the Navy for all its worth in regards to training and opportunities, because it WILL take advantage of you every day you are in it.
Command opportunity. Well, if your ultimate objective is to command then don't go Supply. I have absolutely no desire to command anything. If I were asked to, I would, but that is not my first, second, or third priority or desire. I don't need the title of Commanding Offcier to make things happen and to have a positive effect on my command.
Lower quality of officers and enlisted? How exactly did you come up with that tidbit? There are ****ty Os and Es in *every* community. Yes, even your beloved SEAL community...though I am inclined to say that there are significantly more squared away people in special forces than many other fields. I say this because I have met *numerous* Navy SEALs in the course of my career and just about every single one of them was an amazing individual. Don't label an entire field because some buddy told you something. Get to know people in that field before you forge your own opinion.