In school we simply wrapped masking tape over the cap/tank joint of the Nikkor SS tanks, no more worries of leaking when we inverted the tank.
And as Bill and Sirius said, we could THUMP it on the counter to break air bubbles free, without worrying that we would crack the tank.
If you use a water bath to maintain temp, it is more effective with a SS tank, as SS is a heat conductor. Plastic is a heat insulator, and your water bath won't work as well. But plastic will maintain the temp of the contents.
I learned on SS and find it easier to use. I was the weird guy in class who used the steel tank and reels. Everyone else used plastic.
If you like plastic tank/reels, use it. It is about what works best for YOU, not me.
SS is like a manual transmission car. Harder to learn but one you learn it, it seems easy.
Plastic is like an automatic transmission car. Easy to learn and convenient.
And most/many plastic reels are adjustable, so you can adjust to different size film. SS is one size only.
There are people like Matt who use SS reels for 35mm film but have trouble with the wider 120 film. I don't, but that is just me. They can probably do things that I can't. Everyone is different.
As has been mentioned, if the SS reel was dropped and bent out of alignment, it can be a PiA to load. Trying to bend it back into alignment is HARD. Just throw it away and get a new one. This is the risk of buying old reels, especially the ones with thinner wires. The 35mm 36 exposure reels used a thinner wire than the 20 exposure reels, so if dropped, they bent easier. And some of the cheaper brands bent easier than the Honeywell Nikkor reels that I used.
A comment on the reel itself. If the reel was not finished well, the wire is not SMOOTH. That makes loading film more difficult than with a reel with a SMOOTH finish. The cheaper stuff had the less than smooth finish. I won't say they were hard to load, just not as easy as the reels with smooth finish. So pay attention to the finish of the wires.