As stated, there are 2 charge controllers being marketed as "Solar 30"... one with round buttons and a full aluminum back plate, and one with oval buttons and a combination of aluminum and plastic back plate. I happen to have the first one. I have yet to put it to the test, though.
Now to state the obvious... Unless someone has used both, or knows firsthand; based on either other users' experiences, or on an intimate knowledge of the quality of the internal components of each; that one is better than the other, there is nothing to say on the matter. That said, it is the vendor of the first one that claims their unit is far superior to the latter.
ad comparing the twooval button modelI do wonder if the one aluminum back plate is any better than the other? And I'm sure someone with more knowledge in electronics could comment on the quality of the internal components.